Is it a boy or a girl? The truth behind theories predicting a baby's sex
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There are oft-shared theories about pregnancy: If you carry low, it's a boy. If you've got bad morning sickness, it's a girl.
Why it matters: There's not a lot of evidence that widespread gender predictors are accurate, says Tiffany Pham, OB-GYN and Flo Health medical adviser.
- Still, there is some data supporting certain boy vs. girl suspicions.
Zoom in: Some pregnancy conditions are associated with carrying a boy or a girl — "we just don't know why," Pham says.
When it comes to nausea, studies have found that carrying a girl more often leads to severe morning sickness.
- One possible explanation is the presence of higher hCG levels — the hormone can lead to vomiting.
As for belly sizes, male fetuses can grow faster, which might explain a lower, bigger belly.
- But there isn't definitive information on differences in size between male and female fetuses, Pham says.
And with first pregnancies, women tend to carry higher and not show until about the middle of the second trimester, when their growing belly becomes more obvious.
- That's because ab muscles aren't typically as stretched out as they would be in future pregnancies.
By the numbers: Guessing "it's a boy" will be right more than 50% of the time because more boys are born than girls.
- There's likely an equal number of male and female embryos at conception, but more female embryos are lost in the first half of pregnancy and overall, even though more male embryos are lost later, for unexplained reasons.
- Fertility treatments might also contribute to the fact that there are more boys.
Cultural beliefs can factor in when it comes to predicting the sex of the baby, "but we don't have a ton of data to look at this," Pham says.
- For example, in Asian culture, there's an idea that you look more square if you're expecting a boy. "I'm not really sure how a round belly looks square, but I've heard this before," she says.
We don't have much research on associations with pregnancy symptoms and children who are intersex or transgender.
Between the lines: There are myths about how to conceive a girl or a boy.
The bottom line: "The only accurate way to predict a baby's sex is through non-invasive blood tests, CVS, ultrasound and amniocentesis," says Jane van Dis, OB-GYN and assistant professor at the University of Rochester.
💭 My thought bubble: As I approach my due date, I've been inundated with social media posts about boy vs. girl pregnancy symptoms.
- I've had several (unsolicited) strangers correctly guess my baby's sex — and even the fact that it's my first pregnancy.
- I posted about one such incident on Threads, and got dozens of replies from people with similar experiences. So, here we are.
