Weight Gain Years Before Pregnancy Linked to Excess Gain During Pregnancy, Pitt Study Finds

By: Asher Jones

Pregnancy weight gain above recommendations is linked with bad health outcomes for both mom and baby. A new study found that packing on pounds in the years before conceiving — in both slim and overweight people — is linked with excess weight gain during pregnancy. 

The findings, published recently in Obesity, suggest that assessment of pre-pregnancy weight changes could help identify women who’d benefit from healthy lifestyle interventions such as diet and exercise. 

Dr. Janet Catov

“There’s been a lot of attention on ways to support women to gain healthy weight during pregnancy,” said lead author Dr. Janet Catov, associate professor of obstetrics, gynecology and reproductive services and epidemiology in Pitt’s School of Medicine. “But to really support healthier pregnancies, we probably need to be thinking about a woman’s weight and other factors across the lifespan, not just during the nine months of pregnancy.”  

Gestational weight gain is necessary to support a growing baby, but weight gain above current guidelines is a risk factor for gestational diabetes, preeclampsia and heavier babies — with potential long-term health consequences for mother and child. Women who are overweight or obese have an increased risk of high pregnancy weight gain, but other risk factors for excess weight gain during pregnancy had not been known. 

To learn more, Catov and her team leveraged data from a long-term study called CARDIA that has followed young adults since the mid-1980s to understand cardiovascular disease across the lifespan. Focusing on female participants who gave birth during the study period, the researchers analyzed weight and body mass index (BMI) measurements taken before and during pregnancy. 

They found that the higher a woman’s BMI was before pregnancy, the greater her risk for high gestational weight gain, in line with previous studies. A new finding was that pre-pregnancy weight gain was a risk factor for excess gain during pregnancy — whether a woman was overweight, obese or normal weight.  

On average, a BMI increase of 0.16 per year was associated with an 18% increased risk of excess pregnancy weight gain. For example, women with normal weight who gained 5.7 pounds (2.6 kilograms) in the five years prior to pregnancy had a 40% increased risk of high gestational weight gain compared to those who gained 2.6 pounds (1.2 kilograms). 

“Looking at weight gain patterns before pregnancy could act as a flag for women who might be at risk of gaining excess weight during pregnancy and might benefit from nutritional counseling or other interventions,” said Catov, who is also director of health and clinical research at Magee-Womens Research Institute. “These findings are more evidence that a woman’s health before pregnancy matters for her overall pregnancy health. This means that it’s not just the role of obstetricians to be talking about these issues, but any health care provider.” 

According to Catov, the reason for the link between pre-pregnancy weight gain and excess gestational weight gain is likely due to a combination of factors. The analysis found that participants’ diet quality and physical activity did not explain weight gain patterns.  

“It’s possible that a woman’s physiology might contribute to weight gain,” said Catov. “A metabolism that is primed for weight gain before pregnancy might be more susceptible to the hormonal triggers of gain that are at play during pregnancy.” 

Other lifestyle factors not measured in the study could also contribute to weight gain, including patterns and timing of eating or sedentary time.  

The researchers are partnering with physical activity experts to investigate whether small lifestyle changes could lead to a healthier pregnancy.  

“Pregnant women don’t need to become elite athletes to be healthy,” said Catov. “It’s possible that small changes, such as replacing sitting time with small bouts of activity, are valuable.” 

Catov acknowledged that weight is an “imperfect proxy” for health, and she and her team are developing more holistic metrics of overall wellbeing that include blood pressure, cholesterol levels, diet and activity. 

“The more we understand about the complexity of factors that contribute to weight and other measures of health before, during and after pregnancy, the better-equipped we will be to support women to have healthy pregnancies,” she said.