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We thought about doing myths about Moms, but that might get us in trouble. "Mothers-to-be" aren't as dangerous, at least not to any of us making these videos. So this week we present a whole bunch of pregnancy myths. It's amazing how many of those exist. If you learn one thing this week, let it be that if you have a sperm anywhere near an egg - YOU CAN GET PREGNANT. Enjoy.

Those of you who want to read more and see references can go here: http://theincidentaleconomist.com/wordpress/?p=55348

John Green -- Executive Producer
Stan Muller -- Director, Producer
Aaron Carroll -- Writer
Mark Olsen -- Graphics

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It's Mother's Day! We talked about doing an episode on myths about moms, but then we thought that could get us in some trouble. So, we decided instead to focus on moms to be. They're not as scary, right? So get ready for some pregnancy myths. This is Healthcare Triage.

(Intro)

Pregnancy Myth #1: You can't get pregnant using the "pull out" method. 

Close contact between a penis and a vagina can lead to pregnancy. Period. Even if you use the withdrawal method, it can still be too late. 

Before the male actually ejaculates or climaxes, there are usually already drops of semen at the end of the penis. These drops of semen help to lubricate the head of the penis and may be present before a man feels close to ejaculating. Even one drop of semen can contain a million sperm, and it only takes one sperm.

Sure, there's a smaller chance sperm will fertilize the egg when you start with just one million of them, compared to when you have hundreds of millions as you would in full ejaculation. But it's still possible for one of the sperm out of that drop of semen to make it to the uterus.

Furthermore, the seconds before climax aren't the best time to expect a guy to use good judgment and pull out. Studies show that when a hundred women used this method to prevent pregnancy, twenty three will end up getting pregnant within a year. Even if you pull out perfectly every time, sixteen in a hundred women will get pregnant. Those odds suck. 

Other studies confirmed that this is a terrible method of birth control. In a study of over nineteen hundred women in Turkey, 38% of the women using the pull out method experienced at least one unwanted pregnancy.

In another study from a family planning association, where about 30% of the population reported "the pull out" as their method of choice, about a third of people indicated that they or their partner had become pregnant when relying on withdrawal.

Pregnancy Myth #2: You can't get pregnant during your period. 

For most women, the chance of getting pregnant during their period is slim, but it's not impossible.

A normal period lasts three to five days, but can be as short as two days or as long as seven days. Most women have periods twenty one to forty five days apart, and the cycle tends to shorten and be more regular with age.

If your periods are on the shorter end of the spectrum, or if your periods do not occur in a regular cycle or a certain number of days, there's a greater chance that you will ovulate and thus that you could still get pregnant when your period is going on.

Usually a woman ovulates about two weeks before her period, so that's the most likely time that she could get pregnant. But the egg can live for several days in the Fallopian tube or the uterus. And not all women ovulate exactly two weeks before their period. Some women ovulate much closer to the start of their period, and it's possible that a fertilized egg could survive the shedding of the uterus' lining that takes place during menstruation.

Plus sperm can live for like a week inside a woman's body. Sperm that entered during a period might still be around when that period is done. so with both an egg and a sperm present, whether before, during, or after your period, pregnancy is possible.

Pregnancy Myth #3: You can't get pregnant if you have sex in the water. 

I'm just still amazed this one's a thing. You're just as likely to get pregnant from having unprotected sex in the water as you are from having unprotected sex out of the water. 

Granted, if a man ejaculates in the water, it's pretty unlikely that the sperm will find their way into the vagina and up into the egg, but it's not impossible either.

And if there are living sperm in the vagina, and living eggs around and some way for them to get together, no matter how small or unlikely, you can get pregnant.

Pregnancy Myth #4: You can't get pregnant when you're on the pill. 


In the course of a year, five to eight out of a hundred normal women using the pill will have an accidental pregnancy. Even if you use it perfectly, there's still a one in a hundred chance you could become pregnant.

 Those odds are better than other methods. Remember how crappy pulling out was? But the odds still aren't zero.

Birth control pills work best when taken every day at the exact same time. If you take the pills absolutely perfectly, it's highly unlikely that you'll get pregnant. 

However, if you're forgetful about taking your pill at the same time every day, your chance of getting pregnant while using the pill may be slightly higher. And worse yet, missing even one day of the pill can significantly increase your chance of getting pregnant.

Birth control pills are great in that they're much better than almost any other method at preventing pregnancy, but nothing is a hundred percent.

Pregnancy Myth #5You can predict the sex of your baby without a doctor.

When a woman gets pregnant, she is inundated with people who are sure they can predict the sex of her baby. They can't. They really, really can't. I've got research to prove it, here we go.

Let's start with weight gain and shape of the belly. One study gathered 104 pregnant women, checked the shape of their belly during pregnancy, and found it had no relationship with the baby's sex. Another study of 500 births found that neither the mother's weight, nor her weight gain during pregnancy, helped determine whether her baby was a boy or a girl.

Let's look at heart burn. There's a study that measured how much heartburn 64 pregnant women experienced during pregnancy. They found that the severity of heartburn symptoms had absolutely nothing to do with the sex of the baby. The study did have an interesting finding, though. The more severe a woman's heartburn, the fuller the head of hair on the newborn. Why? Your guess is as good as mine. But again, it had nothing to do with the sex of the baby.

There's "mothers' intuition". And sorry, pregnant women, you suck at predictions too. There was a study of 212 of you, 110 of whom had a "strong feeling" about whether the baby was a girl or a boy. You were all right about half of the time. In another study of 104 women, 55 percent of the women correctly guessed the sex of the baby. But if you calculate the success of the statistics, this was again not any better than they would have done by chance alone. Furthermore, mothers did not do any better whether they made the prediction early, late, or in the middle of the pregnancy.

There's babies' heart rate. Because some people claim that if the fetal heart rate is 140 beats-per-minute or faster, the baby is a girl. If the fetal heart rate has 139 beats-per-minute or lower, then it's a boy. Yeah....No. Scientific data shows that there is no significant difference in the baseline fetal heart rate of a male or female fetus at any recorded gestational age.

Some people...use Drano? I don't know. This one's just insane, but okay. There are actually people that say that if you mix a pregnant woman's urine with Drano, and it turns green, this means she's having a boy. And if it turns brown, she's having a girl. However, other people seem to think that brown predicts a boy and green predicts a---whatever. Thank goodness two physicians from Vancouver evaluated the Drano test in a study, and they found that it doesn't work. Now matter what color the combination turns, it won't help you predict the baby's sex.

And some people talk about morning sickness. And here's the thing. In cases of hyperemesis gravidarum, and I'm talking the very worst kind of morning sickness, which is defined as excessive, unrelenting nausea and/or vomiting that prevents a pregnant woman from taking enough food or fluids in and sometimes requires hospitalization. Then you may have a slightly better chance of having a girl than a boy. Several studies support this finding. However, the difference isn't huge. We're talking a few percentage points, not a conclusive result. So even if you're puking your guts out all the time, the stork could very well be bringing you a boy.

I've got a test for you that works about as well as any of these. Flip a coin. 

Pregnancy Myth #6Flying on a plane is dangerous for your unborn baby.

Unless you've got specific medial problems, or problems with your pregnancy, the American College of Obstetricians and Gynecologists, the biggest group of OB-GYN doctors in the United States, says that pregnant women can fly safely up to 36 weeks of gestation. Now it's possible that the climate of the airplane, including things like low humidity and changes in the pressure of the cabin, do temporarily change an expecting mom's heart rate, blood pressure, and breathing. But not in any way that's been proven to have any detrimental effects on their baby.

One study followed 222 women, of whom 118 traveled by air at least once during their pregnancy. When the physicians compared the two groups, there were no differences in the length of pregnancy, the risk of having a premature baby, the baby's birth weight, the risk of vaginal bleeding, how often babies were admitted to neonatal intensive care units, or any combination of all of these possible things that could go wrong during pregnancy that I just mentioned.

Finally, some pregnant women fear that exposure to noise vibrations, or even to cosmic radiation in the atmosphere, while traveling by airplane, could be harmful. There's not a lot of scientific evidence that has tested whether these are problems for an unborn baby. But the existing studies of the aircraft noise and galactic cosmic radiation exposure during air travel (much of it done on flight attendants who fly way more than you) indicates that any potential risk to a pregnant woman is so small that it shouldn't be cause for alarm.

Pregnancy Myth #7Bed rest prevents preterm labor.

The very common practice of bed rest is based on common sense that strenuous work or play could trigger contractions and labor prematurely. However, the best answer to the question of whether bed rest actually prevents preterm labor, comes from four researchers who conducted a systematic review of the literature looking for studies investigating what happens to women at high risk of giving birth prematurely after they're put on bed rest.

The researchers could only find one study that really investigated the question. But it was a large study, with 1,266 women, and it showed that bed rest did not prevent preterm births. I know that this assertion is going to be met with a lot of angry responses. However, the authors of the systematic review concluded, as do I, that there's no evidence to support bed rest to prevent preterm birth. We have no evidence that it works, and we have one pretty large study that shows that it doesn't seem to work.

And you need to remember that bed rest is not necessarily completely harmless. It can cause problems like deconditioning of the muscles. In addition, unnecessarily preventing mothers from working can create significant problems for a family's finances, and even for society as a whole. It can be incredibly hard on families and cause a lot of needless worry. There has to be a benefit, and that's far from certain.

So whether you got pregnant by accident, or on purpose, happy Mother's Day.