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Researchers are learning more about diet and pregnancy. Getty Images
  • Currently all women who are pregnant are advised to up their calorie intake by about 340 to 450 calories a day in the latter months of their pregnancy.
  • Now a new study finds some women may not need those extra calories.
  • Experts say women still need to find a diet that works for them, especially during the uncomfortable later months of pregnancy.
  • But women with obesity who are pregnant may also face stigma from their healthcare providers.

A growing number of pregnant women in the United States have weight-related conditions like diabetes, high blood pressure, or cardiovascular disease that can increase the risk of pregnancy complications.

However, current guidelines recommend all pregnant women increase calorie intake by 340 to 450 calories per day during the second and third trimesters, regardless of weight at conception.

Now the results of a recent clinical trial evaluating calorie intake, energy expenditure, and weight gain in 54 pregnant women with obesity during pregnancy puts a spotlight on ways this recommendation may need to change.

“We believe that this is the first study to provide evidence-based recommendations for energy intake in pregnant women with obesity that are in contrast to current recommendations by the Institute of Medicine,” wrote the study authors.

But many women with obesity can face stigma from healthcare providers that can also complicate their care.

Researchers observed that weight gain due to increased blood volume, breast tissue, and a growing baby easily accounted for the 11 to 20 pounds that the Institute of Medicine said women with obesity should gain during pregnancy.

According to the researchers, this means that pregnant women with obesity don’t require increased calories to have a healthy pregnancy. Instead they would benefit more from maintaining their prepregnancy calorie intake and focusing on improved diet quality.

The findings contradict accepted recommendations and suggest that existing maternal fat provides enough energy to support healthy fetal growth.

“Two out of every three pregnant women with obesity suffer from excess weight gain, so we conducted an observational study in a cohort of pregnant women with obesity, to better understand what happens to their bodies during pregnancy,” Leanne Redman, MS, PhD, and lead researcher of the study, told Healthline. “We wanted to know how weight gain is affected by changes in diet, physical activity, appetite, and metabolism, and if weight gain is coming from gains in body fat stores and/or non-fat stores.”

Redman admits these findings didn’t surprise her, since excess weight gain is caused by taking in more calories than we need.

“However, we were surprised that to gain the acceptable amount of weight women with obesity should not eat additional calories and should in fact eat slightly less than before they were pregnant,” she added.

Complicating this study is the fact that women with obesity either before or during their pregnancy can also face stigma from their healthcare providers. While experts want to give sound medical advice, they also don’t want to shame patients who are pregnant. This can lead some patients to avoid medical care or become stressed, which can affect the pregnancy.

According to research published in Stigma and Health, while weight gain is part of a healthy pregnancy, women beginning pregnancy who already have overweight can experience negative social responses that make them feel stigmatized.

Another study finds healthcare providers saw pregnant women with overweight as having poorer self-management behaviors, and said they had a more negative attitude towards caring for them, than those with less weight.

This could increase the risk of depression and prevent them from speaking candidly with a healthcare provider about addressing the issue.

Dr. Noelia Zork, maternal fetal medicine specialist at New York-Presbyterian/Columbia University Irving Medical Center, and not associated with this study, explained that the more excess weight someone has, the harder it is to seek help.

“That depends on how overweight you are. Some women who enter pregnancy and they’re just a little overweight, and they’re very cognizant about it — they do want to talk about it because they want to avoid gaining more weight,” she said. “But the patients who are significantly overweight typically have a very hard time bringing it up.”

For all women, Zork emphasized the need for calories typically doesn’t increase until the second and third trimesters.

“The truth is that you actually need more calories for breastfeeding than the pregnancy,” she said. “What’s really important is avoiding foods that carry a risk of bacterial infection.”

In addition to the amount of food, pregnant women are advised to avoid certain common foods due to bacteria.

According to the March of Dimes, exposure to harmful bacteria in some foods can cause illnesses, like salmonella and listeriosis. Symptoms of food poisoning can be worse during pregnancy and even lead to miscarriage or premature birth.

Zork recommends avoiding unpasteurized dairy like certain cheeses or raw milk during pregnancy to reduce this risk. She also believes processed food intake should be limited because they’re generally less nutritious than whole foods.

For women with obesity, eating excessive calories isn’t essential, since a growing baby is well designed to use existing fat stores, according to experts.

Additionally, having overweight during pregnancy can risk the physical health of both mother and child, said Zork.

“For the mother it increases the risk of gestational diabetes, high blood pressure in pregnancy, and increases their risk of C-section.”

“For the baby it increases the risk of birth defects, can cause the fetus to grow really large, and increases risk of a condition called microsomia,” said Zork.

Microsomia is a condition where certain structures of the body are abnormally small.

Obesity “can even increase the risk of stillbirth in pregnancy, although that rate remains overall very low,” added Zork.

Dr. Kirtly Parker Jones, Professor Emeritus at the University of Utah, said in a statement that women shouldn’t worry too much about changing their diet or eating more while pregnant.

“It turns out that the fetus is an excellent parasite. It gets what it needs,” said Jones.

While having overweight during pregnancy can present potentially serious consequences for mother and child’s health, having overweight before pregnancy may also increase the risk of certain health issues. A 2007 study looked at almost 13,000 children to find that mothers with a high body mass index (BMI) before pregnancy had an increased risk of children with ADHD symptoms when they’re school-aged.

New, first of its kind research finds that the current guidelines regarding weight gain for women with obesity during pregnancy may need to be changed.

Researchers found that weight gain due to the normal processes of pregnancy, like fetal growth and increases in breast mass, are enough to account for the 11 to 20 pounds this group of women are recommended to gain.