Everyone knows that gaining excess weight during one pregnancy is bad, but clinicians rarely consider weight gains and losses from one pregnancy to the next--especially in normal-weight women.
But researchers from Marquette University and the University of Michigan found that among normal-weight women, fluctuating weight gain and loss in the first pregnancy is often repeated in subsequent pregnancies--and is associated with higher risk of several pregnancy-related complications.
Interestingly, obese women are not as likely to fall into this weight gain-loss cycle as normal-weight peers, the researchers say. Normal weight is defined as having a BMI less than 25.
Normal-weight women gain more pounds and also lose more after giving birth. This cycle perpetuates with each pregnancy, and it's this rollercoaster weight gain and loss --not just what a woman typically weighs--that predicts poor pregnancy outcomes."
Marianne Weiss, professor emerita of nursing at Marquette
This study says two things. First, don't just look at how much a woman weighs at the first prenatal visit; you have to know her recent pattern of weight gain and loss. Second, pregnancy weight counseling and management should be given equally to all women, not just the ones who are very overweight."
Olga Yakusheva, associate professor at the U-M School of Nursing and School of Public Health
The researchers, who examined 24,795 linked birth records from 2006 to 2013, say first-pregnancy weight gain and subsequent weight loss after birth starts this unhealthy rollercoaster--which in turn increases the risk for gestational diabetes, hypertension, cesarean delivery and fetal macrosomia (bigger-than-average baby) in the next pregnancy.
The study showed that compared with obese women, normal-weight women gained about 6.6 pounds (3 kg) more during both pregnancies and lost about 4.4 pounds (2 kg more) between births.
This surprised Yakusheva.
"I thought that if a lot of weight is gained in the first pregnancy and it was all lost before the second pregnancy, then you're no longer at risk," she said. "Something I didn't consider is that you can be normal weight in the first pregnancy, gain a lot of weight and then lose it before the second pregnancy, and still be at a higher risk of gaining a lot of weight and having negative outcomes in the second pregnancy."
This gain-lose-gain cycle and associated poor pregnancy outcomes reflects Yakusheva's own experience with her two children. Despite rigidly following clinical guidelines with her first child, she added 65 pounds to her 112-pound frame. Neither Yakesheva nor her clinicians noticed or addressed it--she's thin, so weight gain wasn't on anyone's radar.
"I remember the nurses telling me, 'Don't worry about your weight gain, you're tiny,'" she said. "Looking back, I don't think that was healthy for me to hear."
Yakusheva lost the weight before her second pregnancy, yet despite her history, clinicians again didn't address weight gain. Rather, she took it upon herself to monitor her weight.
This doesn't mean weight isn't important, but looking only at weight is myopic, the researchers say. What's more important is how a woman has managed her weight gain and loss in previous pregnancies.
"The bottom line is that women and their perinatal care providers need to pay attention to appropriate weight before, during, and after each pregnancy to set the stage for optimal outcomes in the next pregnancy," Weiss said.
Weiss, M., et al. (2019) Effects of Women’s Weight Changes on Adverse Outcomes in a Second Pregnancy. Science Direct. doi.org/10.1016/j.jogn.2019.08.006.