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Is Morning Sickness Worse With A Girl? Science Seems To Think So

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I had severe morning sickness with my pregnancies. Pregnancy was a personal hell for me, and I hated every minute. However, my first pregnancy with my son was even worse than being pregnant with my daughter. When I tell people this, they're shocked. It turns out that there is a pretty commonly held belief that my morning sickness should've been worse with my daughter because she was a girl. But is there any science to that old wives' tale? Is morning sickness worse with a girl than it is with a boy? Honestly, that was news to me.

There are a ton of old wives' tales regarding the prediction of gender in a baby from the pre-ultrasound world. Everything from a way a mother carries her pregnancy to complex charts drawing on the mother and father's age and birthday are supposed to guess the baby's sex. The idea that your morning sickness will be worse with a girl has always been thought to be just another one of those things that superstitious people have always believed. However, in this case, they might be right. A recent Swedish study found that there is a strong correlation between live girl births and the condition of pregnancy known as hyperemesis gravidarum, a particularly nasty form of severe morning sickness.

According to the study, nausea and vomiting in pregnancy is really common, with almost two-thirds of women experiencing it in some degree. However, the severe form, hyperemesis gravidarum, accounts for only 7 percent of pregnancies, with a strong preference for girl pregnancies. Researchers reported, "There is a marked increase in the probability of observing a girl at (live) birth among those admitted for HG in the first trimester. The coefficient estimates indicate that HG in the first two months of pregnancy raises the proportion of girls at birth by 7 percentage points, from 48.7 percent to approximately 56 percent."

But that's not all. When examining the question of morning sickness being worse with a girl, there are even more factors in play. According to a report by the BBC, girl babies begin producing female hormones while in the womb, and that extra flood of estrogen and progesterone in the mother's womb might bear part of the responsibility for the mom becoming more sick when she's pregnant with a girl than she is with a boy. But because we don't really know what causes the nausea and vomiting of pregnancy, it's mostly just speculation at this point.

Not surprisingly, the severe morning sickness is often inherited. It's passed down from — wait for it — mother to daughter, noted a study in BMJ. That means I can not only thank my mother for my complete lack of ankles, but also my hyperemesis. Thanks, Mom. Women born to women who had severe nausea and vomiting with pregnancy are 73 percent more likely to develop the disorder than women not born to women who've had it, noted an article in Nature.

The same study also found that it might have a genetic component they'd not found previously. They found that two genes, GDF15 and IGFBP7, both "involved in placentation, appetite, and cachexia," also likely have roles in the nausea and vomiting associated with pregnancy, specifically the severe form of hyperemesis.

It's a continually perpetuating issue. A woman who has morning sickness gives birth to a daughter who grows up to be a woman with morning sickness. It's entirely unfair, but honestly, not much about being a pregnant woman is fair, right? Thankfully, it clears up with childbirth, otherwise, I don't think anyone would volunteer for the job.

Check out Romper's new video series, Bearing The Motherload, where disagreeing parents from different sides of an issue sit down with a mediator and talk about how to support (and not judge) each other’s parenting perspectives. New episodes air Mondays on Facebook.