Identical Vs Fraternal: What Your Doctor Didn’t Explain About Your Twin Ultrasound

(or skip to the basics or the science)

I was 7 weeks pregnant when I had my first ultrasound. The doctor pointed out the shared outer sac (chorion) and the two distinct inner sacs (amnions).

I didn’t need her to finish. Thanks to Advanced Placement Bio class in high school (embryonic development) I knew I had a miracle in my womb: identical twins.

Once we’d called everyone we needed to share the good news with, I hit Google, and quickly concluded from their monochorionic/diamniotic (mono/di) state that my little ones had split from a single cluster of identical cells somewhere between 3 and 9 days after conception. I’ll tell you how I made the calculation in a little bit.

The Basics:

Most people don’t know a whole lot about twins or higher order multiples, and are intrigued by them. Folks I run into are usually aware that there are two basic types, identical and fraternal, but often don’t know precisely what the difference is. Part of this comes from the term “identical.”

In casual English, “identical” means “exactly the same,” and so people often assume that identical twins should look alike, act alike, and think alike. This assumption often gets extended to fraternal twins, in that they should look different, act differently, and think differently.

I don’t argue with people about whether my children look enough alike to be “really” identical, and instead give them a quick science lesson.

You’d be surprised how many medical professionals, even obstetricians, don’t remember the science of twinning they covered in the depths of college or medical school, and therefore jump to possibly incorrect conclusions about whether a set of twins is identical or fraternal.

Next time you need to explain the distinction to someone, feel free to use the visual aids below.

The Science:

Identical multiples grow from the same fertilized egg and therefore have basically the same DNA. Fraternal multiples come from different fertilized eggs, and therefore basically share 50% of the same DNA, as do siblings conceived by the same parents at different times. Sharing a DNA template makes it likely that identical siblings will look very much alike, but DNA doesn’t predict everything.

My daughters, for instance, share their DNA, but have noses of different shapes and different hairlines, due to developmental differences that don’t appear to have a genetic basis. They’re also different heights, likely because one is a pickier eater than the other and because dysphagia related to macroglossia (trouble swallowing because her tongue was too big for her mouth) meant that she ate less than Sissy after she weaned.

Vocabulary:

Before I go much further into the science, let’s talk about the terminology we’ve been using.

So, the embryo is inside the amnion, which is in turn inside the chorion. The umbilical cord traverses the two membranes to connect the embryo to the placenta, which collects nutrition from mommy for baby.

Twins in the Womb:

Now let’s talk twins. Monozygotic twins are identical ones. They started from a single zygote. (Mono means one.) Dizygotic twins are fraternal ones. They started from two zygotes. (Di means two.)

Monochorionic/monoamniotic (mono/mono) twins are monozygotic twins who share a single amnion and a single chorion.

Monochorionic/diamniotic (mono/di) twins, like my daughters, are monozygotic twins who have separate amnions and share a single chorion.

Dichorionic/diamniotic (di/di) twins are monozygotic or dizygotic twins who have separate amnions and separate chorions.

I try to make this clearer in the image below. With one egg and sperm, you can get one baby… or two babies who are mono/mono, mono/di or di/di. With two eggs and two sperm, you’ll always get di/di twins.

So here’s the trick. In the image above, you can’t tell the difference between the identical di/di twins and the fraternal di/di twins. And neither can the ultrasound tech. So, if you have di/di twins, chances are good that they’re fraternal, but you just don’t know for sure.

Reader Noura I was kind enough to share ultrasound images of her di/di identical twins, whose ultrasounds look just like those of fraternal twins. Remember, the mono-di stuff refers to the membranes around the babies, and not the numbers of eggs and sperm.

Reading the Ultrasound:

So, in my little chart above, I had to note that there are extraordinarily rare cases of boy/girl identical twins, but this is a teeny tiny proportion of the population. If you ran across such a pair, you’d recognize them from the news.

So, please, just assume that boy/girl twins are fraternal (dizygotic) or that one had a sex change. Either way, it’s not polite to ask. Girl/girl twins and boy/boy twins can be fraternal or identical.

Timing of Monozygotic Twin Split:

Here’s a fun fact. The arrangement of amnion and chorion can tell those of us with identical twins when they split apart!

TTTS can be very serious and put both your babies at risk. The placental blood supply is shared unevenly, meaning that one has more than his or her share of nutrition and oxygen, the other less than his or hers. Many obstetricians will closely monitor mothers expecting twins to watch for TTTS.

While it’s almost unheard of with fraternal twins, reader Halie H. wrote to us to say, “My di/di fraternal (boy/girl) twins’ placentas fused. They were born with one failed and one really really red placenta; they were sent off to be studied as an example of TTTS in fraternals.”

I’m not an expert on this stuff, but I do love genetics and studied it in college (although I ended up switching away from a biology major junior year). If you have additional questions, I’ll do my best to answer them.

Before I sign off, I need to give a big old shout out to Canva.com. I have been planning to write this post for years, but not having an artistic bone in my body, knew that I couldn’t do it justice without an illustrator. Thanks to the free online graphic design tool, Canva, I was able to create the graphics I’ve included in this post.







source: http://hdydi.com/2014/03/12/identical-or-fraternal-a-primer/

12 Weeks Pregnant: Symptoms, Tips, and More

Entering your 12th week of pregnancy means you’re almost through your first trimester. This is also the time that the risk of miscarriage drops significantly.

If you haven’t announced your pregnancy to your family, friends, or people at work, this might be the perfect time for the Big Tell.

Changes in Your Body:

You may still be able to fit into your regular clothes, but they’re probably a little snugger than they were a month ago.

Typically, weight gain to this point is only about 2 pounds. What’s causing your jeans to fit a little differently these days is the other ways your body is preparing to carry your baby. Your uterus, for example, is growing rapidly. Your doctor may be able to feel your uterus in your lower abdomen at this time.

The surge in hormones produces all kinds of changes in your body. One of them is an increase in pigmentation. The “mask of pregnancy” is a condition known as melasma or chloasma. It affects about half of pregnant women, and results in dark spots appearing on your forehead and cheeks.

These spots usually disappear or lighten considerably soon after delivery.

What Bodily Changes Can You Expect During Pregnancy?

Your areolas are likely to become darker at this stage of your pregnancy. Breast tenderness or soreness may continue into the second trimester. A good-fitting bra can be helpful, but make sure it’s the right size. Wearing a bra that has become too tight will make you more uncomfortable.

Ice packs, cool cabbage leaves, or bags of frozen peas on your chest while you lie down may also offer some relief. Look for small, silicone-filled breast soothing products that you can keep in the refrigerator and wear inside your bra.

Your Baby:

Week 12 is a time of big changes for your baby. Your baby is now about three inches long and weighs about 1 ounce. Increased hormone activity means external sex organs should be appearing now or very soon. The fingers and toes aren’t webbed anymore, and fingernails are starting to develop. The eyes will move nearer to each other this week and the kidneys can start to produce urine.

Your baby may also start moving spontaneously this week, though you probably won’t feel it until weeks 16 to 22. Complex reflexes, such as sucking, are also developing right now.

Twin Development at Week 12:

The vocal cords your babies will use to cry and coo are getting ready to develop this week. Their kidneys are also working now. Your babies are approximately 3 inches long, and they each weigh just around an ounce.

Things to Do This Week for a Healthy Pregnancy:

Because you’re gaining weight simply due to the pregnancy, you should pay closer attention to your diet to make sure you don’t gain too much. This can lead to complications such as gestational diabetes, high blood pressure, and pain in your back and legs. Carrying around a lot of extra weight can also lead to greater fatigue.

Don’t avoid eating, either. If you haven’t started following a balanced diet every day, try to end your first trimester on a healthy note. Eat a diet rich in fruits and vegetables, lean proteins, and complex carbohydrates. Avoid junk food. Instead, eat snacks that contain protein, calcium, and minerals, such as yogurt and dried fruit.

Ask your doctor for suggestions or talk with a dietitian. And if you haven’t already, talk with your doctor about taking prenatal vitamins.

Don’t Try Losing Weight While Pregnant:

If your usual diet wasn’t especially healthy up to this point, now is the time to make a change. You and your baby need a variety of nutrients to get through this wonderful but challenging time.

Your skin is also becoming more sensitive. To help reduce the effects of the “mask of pregnancy,” be sure to wear sunscreen with SPF 15 or higher whenever you are outside, and wear a baseball cap or hat to help keep the sun off of your face if you’re outdoors for a prolonged period of time.

Week 12 can be a good time to start doing Kegel exercises to strengthen the vaginal muscles. This can help with delivery and with recovery after the birth.

If you’re unsure how to do Kegel exercises, talk with your healthcare provider. You may also learn about these exercises if you participate in a birthing class.

When to Call Your Doctor:

The risk of miscarriage drops near the end of the first trimester, but it’s still vital that you pay attention to warning signs that could indicate problems. These include:

• bleeding with cramps
• spotting that lasts for three or more days
• severe or crampy pain that lasts all day

By this point you know what normal morning sickness feels like (even if it’s slight nausea experienced throughout the day). If you suddenly feel severe nausea and vomiting more than two or three times a day, please call your doctor immediately.

Encouraging Developments:

For many women, the 12th week of pregnancy is the time that morning sickness symptoms start to ease or even disappear completely. If you’ve been feeling especially tired during the first trimester, you may start getting your energy back at this stage.





source: http://www.healthline.com/health/pregnancy/12-weeks-pregnant

How Moms Cope When Caring for Twins

When you're caring for twins, a routine becomes an absolute necessity. Some moms with single babies can afford to go with the flow, but moms with twins are outnumbered and need a routine to ensure they're able to handle everything.

Routines are excellent for babies and children -- they like to know what's coming next, whether it's lunchtime, naptime, or playtime.

However, this doesn't mean that caring for twins requires that they need to eat at exactly the same time each day. As long as you do regular tasks in the same order each day, your babies will know what's coming next and that's what's important when you're caring for twins.

How Do Moms with Twins Start Their Routine?

The first few weeks may be a blur, but an easy way to start a routine is to watch your twins over a period of about six weeks. They may have their own built-in routine.

Write down when your babies wake up and when they want to eat (you'll probably be quite tired at first, which is why you should write it down! You probably won't remember, even if you try!). If your twins' routines don't match, you can gradually move them toward the middle so you're not worrying about feeding one baby when the other one wants to take a nap.

How to Set a Routine When You're Caring with Twins:

1. Start by setting a bedtime routine. Your routine could start with a special lullaby, a bath or a story.
2. Moms with single babies can let their babies drift off to sleep in their arms, but moms with twins may want their babies to learn to fall asleep on their own. To help, put them down when they're sleeping, but not completely asleep.
3. Your twins may wake each other up, but if one is upset, check that the other one is settled before turning to the upset twin.
4. Resist the temptation to turn on the lights and try to keep your voice low if you speak. If you need a light, use a low-light nightlight so that you don't stimulate your babies.
5. If your babies seem like they're flailing around at night, swaddle them tightly. This can make them feel safe and secure and may help them stay asleep.

How Moms with Twins Ensure a Safe Night's Sleep:

Many moms with twins like their babies to sleep in the same crib at first. However if you're using a small cradle or Moses basket, your babies should have their own sleeping space.

If they're sleeping in the same crib, they should sleep feet to feet with their heads at the opposite sides of the crib. When the babies are big enough to roll around, they should be separated into different cribs.

What Do Experts Say About Caring for Twins?

Experts agree that routines are helpful for moms and babies. Realize though, that babies in the first few weeks of life are unlikely to live by your routine. Enlist your partner to help and consider asking a trusted friend or family member for help if your partner has to go back to work. Consider hiring a postpartum doula, even for a few hours a week. Support is key.

If your babies are in the hospital in the early few weeks, try to spend as much time there as possible. Breastmilk is excellent and there's no reason why moms with twins can't breastfeed. Also, try to practice kangaroo care -- that is, putting your baby skin-to-skin. This can help promote bonding, even if your babies aren't home with you.




source: http://www.mom365.com/baby/moms-health/how-moms-cope-when-caring-for-twins/

Two In The Oven

Facts about twin pregnancies that you might not know.

The twin birth rate in the United States is close to 1 in 31, a nearly 40 percent increase since the early 1980s.

That's because there are growing numbers of older moms (hormonal changes are believed to be responsible for the release of more than one egg at ovulation) and more successful fertility treatments.

Here are some other facts about twin pregnancies that you might not know, from Pregnancy Day by Day editor-in-chief Maggie Blott, M.B., B.S.; and consultant editor Paula Amato, M.D. (Dorling Kindersley):

Research shows that 10 percent to 15 percent of all singleton births may have started off as twins; often one is lost early in pregnancy in a phenomenon known as "vanishing twin syndrome."

The odds of having identical twins (the result when a single fertilized egg splits in two) are about 3 1⁄2 in 1,000.

If you've had nonidentical, or fraternal, twins (the result when two eggs are released at ovulation and both are fertilized) without having taken fertility drugs, your chance of having a second set is about 1 in 3,000.

More than half of twins are born before 37 weeks; plan your maternity leave accordingly so you don't leave your employer in the lurch.

Twins conceived naturally (i.e., without fertility treatment) are most common in the African-American population, followed by Caucasians, Hispanics and Asians. Taller women are also more likely to have twins.

For most women pregnant with twins, gaining 24 pounds by week 24 is advised; a total weight gain of 35-45 pounds is generally desirable.

The twin who is developing closest to the exit (your cervix) is called Baby A. In 75 percent of cases, Baby A is head down before delivery; Baby B may be either head down or breech.

Though vaginal delivery is usually an option, you're more likely to give birth via Cesarean section than if you were having one baby.

Sometimes Baby A is born vaginally, then Baby B is delivered by C-section. This is often the case if Baby B is breech or shows signs of distress because he's gone through two rounds of uterine contractions.

The average birth weight of full-term twins (37 weeks or later, compared to 39-40 weeks for singletons) is around 5 ½ pounds each, though one baby often weighs more than the other.

7 early pregnancy signs

Think you might be pregnant? Here are the most common pregnancy signs in the first month.

When you’re hoping to be pregnant and you haven’t missed your period yet—or it’s a day or two late—it’s pretty easy to interpret nearly any physical symptom as a sign of pregnancy. It’s not uncommon to feel symptoms in the first week or two of your pregnancy—or even earlier.

“Some women experience pregnancy symptoms from the moment of conception,” says Karen Nordahl, a general practitioner and obstetrician in Vancouver and co-author of Fit to Deliver. “Usually, this is second- or third-time moms who remember a particular sensation, such as increased gas.”

But many first-time moms miss these signs because the very earliest symptoms of pregnancy aren’t necessarily the ones we associate with having a baby on the way. So, yes, while some women experience nausea or hypersensitivity to smells, these seven symptoms are among the most common during the first few weeks of pregnancy

1. Increased gas

Being gassy—or, less eloquently, “farty”—is no problem when you’re chillaxing alone in your threadbare sweatpants, but it’s next-level horrifying when you’re out and about anywhere else. Unfortunately, it’s a common sign that you’re pregnant.

Expect flatulence during not only the first few weeks of pregnancy but also the next nine months. Inevitably, your unruly gas will strike right in the middle of a work meeting or during a cool-down in your silent yoga class.

2. Sore breasts

Before you start cursing your bra for suddenly feeling more like a contraption from the hardware store than the lacy lingerie that took a serious chunk out of your paycheque, consider that your newly sore boobs could be a sign that you’re pregnant.

Breast tenderness is another common early sign of pregnancy, according to Nordahl. For many women, what can make this symptom particularly confusing is that breast soreness is also a very common sign of your period.

But early on in your pregnancy, your breasts may hurt because they’re expanding in preparation for producing milk.

3. Heartburn

Digestive changes are one of the most common early symptoms of pregnancy, says Nordahl. If you feel a burning sensation in your chest after scarfing down your usual black coffee and egg-salad sandwich from the deli near your office, it might not be that the deli changed the recipe to include green onions or switched coffee brands; it could actually be pregnancy-related heartburn.

One telltale sign of heartburn is that the burning sensation can feel worse when you bend over or lie down. It’s safe to reach for an antacid to relieve the burning, but also try to avoid certain foods, such as citrus fruits.

4. Bloating

Can’t zip up those light-wash jeans that fit like a glove a few weeks ago? It could be that extra-large soda and popcorn you inhaled while transfixed on the onscreen hunk at the cinema last night, but it could also be a sign that you’re expecting.

Like breast tenderness, abdominal bloating is a symptom that’s common before your period, making it hard to tell apart from monthly premenstrual symptoms. The usual tactic to fight extra bloating is to ease up on excess salt and stay hydrated with water, both of which are good habits, whether you’re pregnant or not. But you might also want to buy a pregnancy test.

5. Lower pelvic cramping

Pelvic cramping as a pregnancy sign? Yep, it can be, according to Nordahl. That might seem counterintuitive, as cramps are super-typical symptoms of Aunt Flow.

You were probably hoping that being pregnant meant you could kiss cramps goodbye, but sadly that’s not the case. Light cramps can be caused by early pregnancy hormonal shifts and implantation of the fertilized egg on your uterine lining.

6. Fullness

The unusual sensation of feeling “full” is yet another early sign of pregnancy. “Fullness can be experienced before a period is missed, but a first-time mom may miss it,” says Nordahl. “A second- or third-time mom may pick up on it right away, especially if she is actively trying to conceive.”

If you’re getting a feeling of déjà vu from previous pregnancies that you’re experiencing at the gut level (literally), congrats, you could be preggo!

7. A missed period

Well, duh, of course a missed period is an early sign of pregnancy. For many women who haven’t been pregnant before, this is usually the first symptom they notice, explains Nordahl.

But hindsight is often 20/20. “A first-time mom usually thinks back and realizes that a few things were different but wasn’t sure what they meant,” she says.





source: http://www.todaysparent.com/trying-to-conceive/getting-pregnant/7-early-pregnancy-signs/

First Signs of Pregnancy - Early Symptoms of your First Trimester

Before my first pregnancy, I enjoyed a glass of wine with dinner and an occasional big, juicy chili dog. But even in those very first days after I conceived, the wine tasted flat and the hot dog repulsed me. Fast-forward a few weeks. With a positive pregnancy test in hand,

I realized that my body knew I was pregnant before my mind did. Of course, the earliest symptoms of pregnancy wax and wane and are different for each woman; in fact, some women may experience (or notice) none of them.

But several can crop up well before you even miss a period. If you’re the impatient type, here are the most common early-pregnancy clues to look for.

Clue 1} Breast tenderness Your breasts may be extra tender as early as a week or two after conception. “You’re making so much estrogen and progesterone in early pregnancy that the glands in the breasts start growing,” explains Jasbir Singh, M.D., an OB-GYN at Baylor Medical Center at Waxahachie in Texas. This hormone surge causes breasts to retain more fluids and feel heavy, sore or more sensitive than normal PMS tenderness.

What to do Buy a very supportive bra.

Clue 2} Implantation bleeding When the fertilized egg implants into the plush lining of the uterus about six to 12 days after conception, spotting—light vaginal bleeding—may occur. This is harmless, but if you suspect you’re pregnant, let your doctor know, just in case it’s something else. (If the bleeding occurs as late as 12 days after you conceive, you may think it’s your period.)

“In the first trimester, bleeding should be evaluated for three things in particular—miscarriage, an ectopic pregnancy or certain types of infections,” Singh says. “Implantation bleeding is sort of a diagnosis of exclusion. That means we rule out the bad things before we can determine this is what it is.”

What to do Call your doctor if you notice any bleeding.

Clue 3} Fatigue During the first few weeks, your body is working 24/7 behind the scenes to support the pregnancy, and fatigue is a normal response. The extra progesterone produced after conception causes your basal body temperature to rise, which in turn contributes to a lack of energy, explains Karen Perkins, M.D., an OB-GYN with A Woman’s Choice at Mercy Medical Center in Baltimore. Your heart also pumps faster, as it has to deliver extra oxygen to the uterus; this, too, can make you feel tuckered out.

What to do “Take prenatal vitamins early on, eat a healthful diet, drink plenty of fluids to keep your blood pressure high enough, and rest when you can,” Singh says.

Clue 4} Frequent urination You might think this comes later, when the baby presses on your bladder, but frequent peeing sometimes starts early. Not only can the swelling uterus put pressure on your bladder, but the extra blood flow to the kidneys (which begins right away) also causes them to produce more urine.

What to do Nothing, unless the frequent urination is accompanied by burning, urgency or other signs of infection. (If so, notify your doctor.) Do not cut back on your fluid intake.

Clue 5} Food aversions and nausea This can start as early as two weeks after conception. “Progesterone causes a lot of things to slow down,” Singh says. That includes your digestive processes, sometimes resulting in constipation or indigestion.

Since your stomach doesn’t empty as quickly as it normally does, it thinks there’s too much going on in there and wants to purge in some way—either into the gut or out through the mouth. Nausea also is related to human chorionic gonadotropin (HCG), a hormone that can be detected in the mother’s blood or urine even before a missed period. The higher the HCG level (as with twins), the sicker you may feel.

“Another theory is that nausea and food aversions are a protective effect the body has toward the fetus,” Perkins says. If things like free radicals or nitrates in some foods could hurt a growing baby, you may naturally develop a distaste to steer clear of them.

What to do Many women find ginger and lemons soothing. Ask your doctor about special vitamin B6 supplements that may alleviate nausea. Acupressure wristbands also can help. If you’re vomiting frequently or can’t hold down any liquids, see your OB for possible IV hydration and medication.

Clue 6} Mood swings Find yourself weeping over a “Desperate Housewives” episode or raging because the DSL guy can’t come until Tuesday? “Because of the flux in hormones, you can go from being tearful to angry instantly,” Perkins says. Generally, mood swings in early pregnancy don’t require any medical attention.

What to do Wait it out. “Be aware of your mood shifts and make sure others around you also are aware of the reason and are supportive,” Perkins suggests.

Clue 7} Bloating, cramps and backache Many women mistake these common early signs of pregnancy for PMS symptoms, but actually they’re caused by hormonal changes and the growth of the uterus.

What to do Nothing, unless the pain is severe or symptoms are accompanied by bleeding. Clue 8} Dizziness and fainting

On soaps, the woman always faints before she finds out she’s pregnant. Progesterone can contribute to lightheadedness by making your body “run hotter” and causing blood vessels to dilate, which lowers blood pressure.

In addition, it takes a little longer than normal for blood that’s been diverted to the uterus to make its way back to your brain when you stand up. Dizziness also can stem from low blood sugar. “If you’re not eating properly, you can feel lightheaded,” Perkins says.

What to do Move slowly, and don’t leap out of bed or off the couch abruptly. Keep blood sugar stable by eating every three to four hours, and drink plenty of water to keep your blood pressure steady. Avoid overheating, and if you do feel faint, sit down with your head between your knees.

Clue 9} Headaches Some women have more headaches early in pregnancy. “They’re related to the increased progesterone levels; plus, headaches can result if you don’t drink enough fluids or if you’re anemic,” Perkins says.

The good news: Migraines become less frequent as pregnancy progresses. “Fluctuating hormones tend to make headaches worse, and estrogen levels are more stable during pregnancy,” explains Richard Gersh, M.D., an assistant professor of OB-GYN at Drexel University College of Medicine in Philadelphia.

What to do Drink plenty of fluids, and get your blood work done to check for anemia. If headaches persist, ask your doctor about taking Tylenol.




source: http://www.fitpregnancy.com/pregnancy/getting-pregnant/first-signs-pregnancy-early-symptoms-your-first-trimester

11 Facts About Twins That Make Them Even Cooler Than You Already Thought

The number of twins in the U.S. is multiplying. According to a 2012 report by the National Center for Health Statistics, their birthrate rose 76 percent from 1980 to 2009.

This could be due to the fact that more women over the age of 30 are having children and more are using fertility drugs and assisted reproductive technology, both of which increase the likelihood of multiple gestation. As many as one in three women who use fertility treatments may become pregnant with twins.

The result? As many as one in 30 babies born in the United States is now a twin. A recent report published in the New England Journal of Medicine says that by 2011, the incidence of triplet or higher-order births decreased by 29 percent from its peak in 1998.

Researchers attributed this trend — in part — to changes in medical guidelines aimed at reducing multiple births resulting from IVF. (A recent study found that other fertility treatments, such as ovulation-inducing medications or insemination, have overtaken IVF as the main source of multiples resulting from fertility treatment.)

With so many twins among us these days, it’s high time we celebrate some of the most interesting facts about them.

1. Identical twins do not have identical fingerprints:

You might think that because identical twins supposedly share almost the same DNA, they must also have identical fingerprints. Well, that’s not true. Fingerprints are not solely generated based on DNA.

When identical twins are conceived, they start out with the same fingerprints, but during weeks six through 13 of pregnancy, as the babies start to move, they each touch the amniotic sac, and unique ridges and lines are formed on each twin’s hand that result in different fingerprints.

2. Massachusetts has the most twin births of any state in                 America:

At nearly 4.5 for every 100 live births, Massachusetts has the highest rate of twin births. Connecticut and New Jersey follow with 4.2 twins per every 100 births.

Researchers hypothesize that more multiple births occur in “affluent towns outside of Boston” because of a higher concentration of wealthier women who have pursued careers.

These women are more likely to attempt to have children at a later age and seek reproductive assistance. The state with the lowest rate of twin births is New Mexico.

3. Mirror image identical twins have reverse asymmetric                 features.

About 25 percent of identical twins develop directly facing each other, meaning they become exact reflections of one another. According to About.com, “they may be right- and left-handed, have birthmarks on opposite sides of their body, or have hair whorls that swirl in opposite directions.” This occurs when the twins split from one fertilized egg more than a week after conception.

4. Identical twins do not always have the same genetics:

While identical twins derive from one fertilized egg that contains a single set of genetic instructions, also known as a genome, it’s still possible for identical twins to have serious differences in their genetic makeup.

Geneticist Carl Bruder of the University of Alabama at Birmingham closely studied the genomes of 19 sets of adult identical twins and found that in some sets, one twin’s DNA differed in the number of copies of each gene it had.

Normally, every person carries two copies of every gene, one inherited from each parent, but Bruder explains that there are “regions in the genome that deviate from that two-copy rule, [and] these regions can carry anywhere from zero to 14 copies of a gene.”

5. Mothers of twins may live longer:

A study published in the journal Proceedings of the Royal Society B focused on the population of women in 1800s Utah and found that women who gave birth to twins were very strong and healthy to begin with, so were likely to live long lives.

As LiveScience writer Stephanie Pappas explains it, “Twins could be an evolutionary adaption in which healthy moms take the chance to pass on double their genes at once.”

However, because the data only includes women who conceived twins naturally — IVF was obviously not used in the 1800s — the findings are not definitive.

6. Tall women are more likely to have twins:

Gary Steinman, MD, PhD, an attending physician at Long Island Jewish (LIJ) Medical Center, discovered that taller women have more insulin-like growth factor (IGF), a protein that is released from the liver in response to a growth hormone that stimulates growth in the shaft of longer bones.

Having higher levels of IGF results in increased sensitivity of the ovaries, thus increasing a woman’s chance of ovulating. According to Steinman, the more IGF a woman has, the greater chance she has of becoming pregnant with twins, because IGF “govern[s] the rate of spontaneous twinning.”

7. Also, women who eat a lot of dairy are more prone to                   conceiving twins:

Another study done by Steinman and published in the Journal of Reproductive Medicine found that women who eat more dairy products may increase their chances of conceiving twins. Steinman tested this by comparing twin rates from vegan mothers and non-vegan mothers.

Those who consumed dairy were five times more likely to have twins. This is because cows, like humans, also produce IGF in response to growth hormone and release it into their blood. Then it gets released into their milk, which women consume.

8. It’s possible that twins can have different dads:

In 2009, Mia Washington gave birth to twins who have different fathers — which is said to be a one-in-a-million occurrence. Dr. Hilda Hutcherson, Clinical Professor of Obstetrics and Gynecology at Columbia University, explained to “Today” how it happened: Normally, a woman releases one egg each month. For Washington, there were two.

At the same time, the mom had intercourse with two different men in the span of five days. Because sperm can remain alive in the reproductive tract for that long, each man’s sperm fertilized one of eggs. Voila! Two babies, two dads.

9. Twins interact with each other in the womb:

In 2011, researchers at Umberto Castiello of the University of Padova in Italy studied 3D videos of twins in their mother’s womb. At 14 weeks of gestation, twins were seen reaching for each other.

By 18 weeks, they touched each other more often than they touched their own bodies. The researchers said that kinematic analyses of the recordings revealed that the twins made distinct gestures toward each other and were as gentle to the other twin’s delicate eye area as they were when they touched their own.

10. Some conjoined twins can feel and taste what the other one         does:

Susan Dominus wrote a piece for The New York Times about two conjoined twins, Krista and Tatiana Hogan, who are attached at the head through a “thalamic bridge,” part of the brain that acts as a sort of “neural switchboard” and filters most sensory input. Scientists have hypothesized that this connection could result in one Hogan sister being able to taste and feel what the other twin is experiencing and to understand each other’s thoughts. Dominus, who spent a considerable amount of time with the twins for her story, recorded these amazing observations:

“[Their parents noticed] when one girl’s vision was angled away from the television, she was laughing at the images flashing in front of her sister’s eyes. The sensory exchange, [researchers] believe, extends to the girls’ taste buds: Krista likes ketchup, and Tatiana does not, something the family discovered when Tatiana tried to scrape the condiment off her own tongue, even when she was not eating it.”

11. Forty percent of twins invent their own languages:

These languages are called autonomous languages. Researchers suspect that twin babies use each other as models in developing language when an adult model language is frequently absent. The “language” consists of inverted words and onomatopoeic expressions.

These autonomous languages are formed when two very close babies are learning how to speak a real language alongside one another and naturally often play and communicate with each other.

While this is more common among twins, since they are more likely to be around each other and developing at the same rate, this phenomenon can also sporadically occur between two babies who are not twins. The made up “languages” often disappear soon after childhood, once the children have learned a real language.




source: http://www.huffingtonpost.com/2014/03/24/twin-facts_n_4959012.html