New study suggests diet, stress management might reduce fetal growth restriction risks

December 21, 2021

Robyn Horsager-Boehrer, M.D. Obstetrics and Gynecology

Research shows that eating healthy foods and managing your stress can have a positive effect on your pregnancy.

While no two babies grow exactly the same, fetal measurement milestones are an important indicator of healthy organ development. During prenatal appointments, your doctor will measure from the top of your uterus to your pubic bone to estimate the baby’s size. The length should approximately match the number of weeks you’ve been pregnant: 20cm at 20 weeks, for example.

Many babies that measure small for gestational age (SGA), or less developed than expected at that point in pregnancy, will be perfectly healthy. But for some, small measurements might be a sign of fetal growth restriction (FGR).

Babies affected by FGR are under the 10th percentile for estimated fetal weight measured by ultrasound – smaller than 90% of fetuses of the same gestational age. FGR can lead to premature birth, stillbirth, and ongoing development problems after birth.

FGR can be caused by genetic abnormalities, improper placental development, or maternal risk factors, such as autoimmune conditions or pregestational diabetes. Though there are no standard guidelines for preventing FGR, a new study suggests that high stress levels and poor nutrition are two factors that may increase your risk.

Diet, stress, and fetal growth restriction

Researchers in Spain recently conducted a randomized clinical trial – the IMPACT BCN Trial (Improving Mothers for Better Prenatal Care) – of nearly 1,200 pregnant patients at high risk of having an SGA newborn. They were considered high risk based on having one or more “major” risk factors or three or more “minor” risk factors.

Major risk factors include:

Abnormal uterine arteries in the first trimester
Autoimmune disorders
Being age 40 or older
Chronic high blood pressure
Daily vigorous exercise
Diabetes
Drug use
Previous pregnancy with FGR, stillbirth, or preeclampsia before 34 weeks
Kidney disease
Smoking at least 11 cigarettes a day

Minor risk factors include:

Being age 35 or older
BMI below 20 or above 25
Never giving birth
Previous pregnancy with preeclampsia after 34 weeks
Smoking 1-10 cigarettes a day

Patients were randomized into three groups at 19-23 weeks of pregnancy. All groups received standard prenatal care, and two groups also either adopted the Mediterranean diet, which features healthy, plant-based meals, or regularly practiced mindfulness-based stress reduction exercises.

The results suggest that stress and diet interventions reduced the risk of FGR. The percentage of newborns with birth weight below the 10th percentile was:

14% in the Mediterranean diet group
15.6% in the mindfulness-based stress reduction group
21.9% in the standard prenatal care group

Percentages of babies with any major morbidity, such as preterm birth, stillbirth, or extremely low birthweight, also decreased in the groups who received diet or stress intervention. Complications affected 18.6% of babies in the Mediterranean diet group and 19.5% in the mindfulness group, compared to 26.2% in the standard care group.

Improving long-term health with sustainable eating habits

Previous studies have focused on specific food groups’ effects on FGR. The IMPACT BCN Trial aimed to change participants’ eating habits in sustainable ways. Researchers encouraged participants in the diet group to change their eating patterns and the way they viewed and made choices about food.

Participants attended individual and group education sessions conducted by registered dieticians. They also received free extra-virgin olive oil and walnuts – two important sources of fatty acids that support fetal development and reduce the risk of blood clots and heart disease.

Try increasing the amount of fruits and vegetables in your diet.

Individuals were encouraged to avoid all alcohol, cook often with extra-virgin olive oil, tomatoes, garlic, and onions, and eat:

Three or more servings of walnuts, legumes, and seafood each week
Three or more daily servings of vegetables
Two or more daily servings of fresh fruits and dairy products
White meat instead of red meat
Whole grains instead of refined grains
Limited amounts of cream, butter, margarine, and baked goods

Participants’ body weight, abdominal circumference, blood pressure, and heart rate were measured at each follow-up visit to help them track the health benefits of their new eating patterns.

The Mediterranean diet is often recommended for heart health, thanks to its emphasis on eating more plant-based foods and less saturated fat and sugar. More than any other eating pattern, the Mediterranean diet is more of a lifestyle than a dietary plan, as it also encourages regular exercise and enjoying meals with friends and family.

Related reading: How to combat heart disease during pregnancy

Mindful stress reduction showed positive results during the clinical trial.

Managing stress with mindfulness

Stress is unavoidable, but our reaction to it can harm our health. Unmanaged stress can lead to chronic conditions such as heart disease, depression, and high blood pressure. Fortunately, mindful meditation can reduce it.

During the IMPACT BCN Trial, participants in the stress group attended an eight-week stress reduction program adapted for pregnancy and based in mindfulness – becoming aware of and accepting your thoughts, feelings, emotions, and senses in the present moment.

Daily practice was encouraged so they could improve their ability to:

Pay attention to what they experience “in the moment” during pleasant and unpleasant events
Stop and breathe when necessary
Stay present during routine activities such as eating, driving, walking, and feeling baby movements
Recognize their emotions and reactions to stress

Through group sessions and recorded instructions, participants learned meditations that focused on being “present” with their baby. They also learned prenatal yoga positions and how to work through difficult thoughts and emotions.

Related reading: Tips to manage 'pandemic pregnancy' stress

The future of FGR prevention

The IMPACT BCN Trial was a novel approach to reducing the risk of FGR. More research is needed to replicate these results and produce more evidence that the tactics can work consistently.

Considering the study participants were at high risk for FGR, these results might only reoccur in other high-risk populations. But the potential for new, safe tools that can empower patients to improve their own health and reduce the risk of FGR is very exciting.

Your health can significantly affect your pregnancy. If you’re feeling stressed or want help incorporating healthy foods into your diet, talk with your provider. We’re here to help you feel better and live healthier – before and after giving birth.

To visit with an Ob/Gyn, call 214-645-8300 or request an appointment online.