Spurred by the revelation that Meghan Markle and Prince Harry are expecting their first child, the Cut did some research into the science behind baby bumps. Specifically: Why do baby bumps look so different on different women? In one photo I came across of two women in the same trimester, for instance, one looked hugely pregnant while the other was barely showing. My mind was blown. Why? How?
Typically, baby bumps become visible in the 12 to 16 week range, because “the uterus does not leave the pelvis until after 12 weeks,” said Dr. Shannon M. Clark, an associate professor of obstetrics and gynecology at the University of Texas Medical Branch at Galveston. Beyond that, though, it’s hard to define a “typical” bump. Angela Garbes, author of Like a Mother: A Feminist Journey Through the Science and Culture of Pregnancy, emphasized that there is no “standard” when it comes to baby bumps (or pregnancy for that matter). A baby bump is “a protrusion,” she said, but it’s not always “a joyful bump” with “glowing-orb-of-life” vibes — and it can look very different in different women. For instance, she mentioned A.K. Summers’s graphic novel Pregnant Butch, in which the protagonist feels like a fat man with a beer belly. “There are as many ways to be and look pregnant as there are people who get pregnant,” Garbes told me. “Which is to say: an infinite variety.”
But there are some common factors that determine the shape of a baby bump:
Being a first-time mom. Bumps often appear later in first-time moms, because their abs haven’t been stretched from prior pregnancy, whereas the ab muscles on women who’ve already borne a child may be “more lax,” and thus readier to reveal a protruding uterus. Also: “First-time moms tend to carry their babies higher, whereas multiparous moms can carry the baby lower,” Clark said. (Multiparous: having borne more than one child.)
Carrying twins (or more). Not only can women carrying multiple fetuses be “bigger at every stage in pregnancy,” Clark said, but the shape of their pregnancies “can be wider from side-to-side as well as from front-to-back.”
Getting close to delivery. As a pregnancy enters the third trimester, Clark said, rather than taking on a typical “balloon shape” appearance, “the uterus can appear to be more ‘misshapen,’ due to the varying positions of the babies. Heads, butts, arms, and legs can be very pronounced!”
Obesity. Obese women tend to show later in pregnancy, often in the late-second or third trimester.
Having a tilted uterus. “A woman who has a retroverted uterus,” Clark said, “can develop a baby bump later in the second trimester, when the uterus finally assumes a more typical position.” An extremely anteverted uterus, however “may ‘show’ through a earlier baby bump, especially in multiparous women.”
Most important, Garbes said, is that although “we have this idea of what a ‘normal’ pregnancy looks like,” thanks to mainstream portrayals, “that’s just not what it’s like for a lot of people.” But she understands the preoccupation: “Part of the fascination with the bump and with pregnancy in general is that it’s just very cool,” she said. Indeed it is.