How Stress During Pregnancy Affects Mother and Baby

Severe stress can hurt growing babies, but experts say mild day to day stress won’t have the same negative effects

InIn many ways, a mother’s health during pregnancy is intertwined with her baby’s health in the womb. A high fever, for example, if it’s left untreated, can interfere with the development of a fetus’ heart and jaw. And if a woman doesn’t get enough of the nutrient folate during the first trimester, the baby’s spine may not develop properly (which is why many practitioners recommend beginning a prenatal vitamin before getting pregnant, when possible).

Given the strong physiological connection between the two, it comes as no surprise that a mother’s stress during pregnancy can also affect the growing baby.

Severe stress has long been known to increase the risk for negative pregnancy outcomes, potentially leading to preterm labor or reduced birth weight. But a growing body of recent research shows that the effects of prenatal stress, including untreated anxiety or depression, could affect babies long after birth, possibly carrying over into childhood and even adulthood.

One study shows that prenatal stress can result in more aggressive toddlers: Mothers who reported higher anxiety and stress during pregnancy were more likely to have two-year-olds who displayed behavioral problems like temper tantrums, restlessness, and spitefulness. Other research links exposure to stress in the womb to an increased risk of mood disorders and difficulty regulating emotions as early as six months of age.

While research has consistently proven stress to be a threat to growing babies, not all stressful experiences have the same, potentially harmful effect. Doctors say the longer the duration and intensity of a mother’s stress, the higher the likelihood of effects on the baby.

“We’re talking about women who are being emotionally, physically, or sexually abused, not women who have a stressful job. That hasn’t ever been shown to be associated with poor pregnancy outcomes.”

“The impact of stress on the baby will be determined by the severity of the variation and context of the stress exposure,” says Nikki Zite, MD, an OB-GYN with the University of Tennessee Medical Center. “For example, if a woman experiences repetitive trauma through domestic violence, her baby is probably more at risk than if she is in a minor car accident.”

Long-term, or chronic, exposure to trauma is the kind of stress most doctors worry about when it comes to maternal-fetal health. In fact, Peter S. Bernstein, MD, MPH, director of maternal fetal medicine at Montefiore Health System and professor of obstetrics and gynecology and women’s health at the Albert Einstein College of Medicine, says the majority of research on the effects of prenatal stress focuses on significant, traumatic events.

“We’re talking about women who are being emotionally, physically, or sexually abused, not women who have a stressful job. That hasn’t ever been shown to be associated with poor pregnancy outcomes,” he says.

IfIf a mother is exposed chronically to significant stress — for example, if she lives in a highly stressful environment, doesn’t have enough food, or is a victim of chronic, systemic racism — these constant threats will trigger the fight-or-flight response.

In the short term, the release of cortisol is part of the body’s automatic way of protecting itself from perceived harm — but, long term, chronic stress can lead to a number of negative health outcomes, from high blood pressure and weight gain to heart disease and weakened immunity, all of which can impact babies’ health.

While cortisol has generally been thought to be the culprit behind many of these adverse outcomes, only recently have researchers begun to uncover exactly how the stress hormone affects babies’ developing brains and bodies. In a 2019 lab study, Nadine Provencal, PhD, assistant professor of health sciences at Simon Fraser University in British Columbia, researched how cells in an early phase of development change in the presence of cortisol — essentially mimicking a developing fetal brain in a petri dish.

Not only did the young cells’ neurons react immediately to the cortisol, but when the hormone was introduced again later on, they reacted much more than cells that hadn’t earlier been exposed — implying that babies exposed to cortisol in the womb may have a higher vulnerability to stress, even after birth. Basically, Provencal says, the “stressed” cells have genetic markers, or cellular memories, of stress long after they are fully developed, which causes them to be more sensitive to stressful cues. “We have a hint into how prenatal stress exposure might lead to increased stress reactivity later on by changing this memory of neurons in our brain,” she says.

TThere’s also evidence that chronic stress increases a woman’s risk for anxiety and depression, both of which, if left untreated, can be detrimental for the fetus. Anxiety and depression increase the release of cortisol, which can have negative effects on its own. But, if left untreated, depression can also lead the mother to rely on unhealthy behaviors to cope, which can be just as dangerous for a baby as her stress.

For example, Zite says high levels of stress due to mental illness in pregnancy can lead to less nutritious eating, isolation, lack of exercise, and more concerningly, drug and alcohol use.

Drinking alcohol during pregnancy has been linked to fetal alcohol syndrome, a severe disorder that, in addition to facial abnormalities, can cause growth problems, mental disabilities, and behavioral problems in babies and children. Illicit drug use during a mother’s pregnancy comes with similar risks for children, such as behavioral problems, hyperactivity, and learning disabilities.

There’s also the issue of mental illness extending after pregnancy, which can negatively influence the mother’s relationship with her baby post-birth. Women who experience trauma or mental illness during pregnancy are at a higher risk for postpartum mood disorders, which Zite says can contribute to difficulty with breastfeeding, trouble in bonding, and in some, severe cases, violence toward oneself or others.

WWhen it comes to treating a pregnant woman’s mental health, the discussion around whether or not women should take antidepressants or anti-anxiety medication during pregnancy continues to evolve. The current consensus is that if the risk of stress on a baby or mom is greater than the risk of a medication, the medication may be a better option.

It’s important to remember the symbiotic relationship between maternal and fetal health.

Alexandra Sacks, MD, a reproductive psychiatrist, coauthor of What No One Tells You: A Guide to Your Emotions From Pregnancy to Motherhood, and the host of the podcast Motherhood Sessions, says all medications — from steroids to treat asthma, to antidepressants to help a mother manage stress — come with risks, but that doesn’t mean there’s not a time or place to use them in pregnancy.

“Whether it’s a physical symptom or a psychiatric one, we think of the well-being of the mother and baby as being interconnected — so for every case, a risk-benefit analysis is used to assess the safest treatment plan,” she says.

The most important thing, Sacks says, is for a woman facing significant stress or mental illness during pregnancy to talk to an OB, and not to make any decisions about medication beforehand. If possible, Sacks also suggests a consultation with a reproductive psychiatrist, who may be more well-versed in the potential risks of anti-anxiety medication or antidepressants.

InIn spite of the research showing the potentially significant effect of stress on fetuses, some clinicians are wary of putting even more pressure on parents. In some cases, focusing too much on stress and stress reduction could be counterproductive, causing even more unnecessary anxiety. “My approach is to tell women not to worry so much about stress,” says Bernstein. “We want the pregnancy to be a joyful experience.”

But for women experiencing chronic, ongoing stress, Provencal’s work serves as a reminder of the potentially lifelong imprint women’s health can have on their children’s growing brains. Provencal says she believes it’s important for parents to focus on reducing their children’s exposure to excessive stress, even in the womb. It’s important to remember the symbiotic relationship between maternal and fetal health.

“When you’re pregnant, everything from your environment to your health will definitely eventually impact your child in one way or another,” she says. “We need to try to create the best environment we can with what we have.”

Writer-mom hybrid. Health & psychology stories in NYT, WaPo, Allure, Real Simple, & more.

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