Vegetable intake before pregnancy reduces risk of preterm birth

By Dr. Ananya Mandal, MDApr 15 2020

A new study shows that women who eat vegetables regularly before becoming pregnant have a significantly lower risk of premature birth. The new study from the University of Queensland titled, "Prepregnancy dietary patterns and risk of preterm birth and low birth weight: findings from the Australian Longitudinal Study on Women's Health," was published in the latest issue of the journal The American Journal of Clinical Nutrition.

Study: Prepregnancy dietary patterns and risk of preterm birth and low birth weight: findings from the Australian Longitudinal Study on Women's Health. Image Credit: Cmp55 / Shutterstock

What was this study about?

Researchers explain that there have been several studies in the past that show that diet before a woman gets pregnant could be associated with preterm birth as well as low birth weight (LBW) in the babies. These studies, however, are not conclusive, they write. This study was undertaken to see if diet before getting pregnant could affect the risk of having preterm births and low birth weight babies.

Ph.D. candidate Dereje Gete explained that many women have poor diets before they are pregnant, and this could be affecting their course of pregnancy adversely. The study defines preterm births as babies born before 37 weeks of pregnancy. Studies have shown that preterm babies have a higher risk of death during the neonatal period and infancy, and among Australian children, preterm birth can affect 8.5 percent of all births annually. Experts say that the rates of preterm births are on the rise across the nation.

What was done?

For this study, diet records of 3,422 women and 3,508 live births with single babies were extracted from the Australian Longitudinal Study on Women's Health (ALSWH). The ALSWH is a study involving over 57,000 women and looks at various factors such as social, physical, environmental, biological, and lifestyle-related or behavioral that affect their health and well being.

The women included in this subset study did not have previous childbirth and were non-pregnant at the beginning of the study. To assess the diets of these women participants, the team used the "Healthy Eating Index-2015 (HEI-2015) score". Using this, they found the dietary patterns of these women.

From the study, they outlined four different dietary patterns among the non-pregnant women who got pregnant later during the study. These four were;

• Those primarily eating meats and high-fats.
• Those primarily on prudent diets.
• Those mainly on sugar, refined grains, and processed foods.
• Those with a diet mainly comprising of traditional vegetables.

From the participants, assessment of preterm births and low birth weight babies was assessed from maternal records and ALSWH data gathered between 2003 and 2015. The team used multivariable logistic regression analyses to look at the association between pre-pregnancy diet and the outcomes of the pregnancies. Some of the traditional vegetables included broccoli, cabbage, carrots, cauliflower, green beans, potatoes, and pumpkin.

What was found?

The study revealed that women who ate more traditional vegetables before pregnancy were less likely to have preterm births. The team adjusted all the other influencing factors and lifestyle factors that could have raised the risk of preterm births and low birthweight babies before coming to their conclusions. The odds ratio was 0.72, and the relative risk ratio was 0.62, they wrote. They added that these risks of preterm births and low birth weight babies were not linked to the body mass index of the mothers before they were pregnant. There was no association of pre-pregnancy dietary patterns and low birth weight babies, the team found.

Mr. Gete said, "Traditional vegetables are rich in antioxidants or anti-inflammatory nutrients, which have a significant role in reducing the risk of adverse birth outcomes. Women depend on certain stored nutrients such as calcium and iron before conception, which are critical for the placenta and fetus tissue development. Starting a healthier diet after the baby has been conceived may be too late because the end of the first trimester fully forms babies."

Conclusions and expert speak

The researchers in this study say that women should consume more of the traditional vegetables before getting pregnant to improve the outcomes of their pregnancies.

They write, "This study suggests that better adherence to the traditional vegetable pattern before pregnancy is associated with a lower risk of preterm birth, particularly spontaneous preterm birth among nulliparous women."

The team, however, adds that more studies are needed to see if this association holds true for large populations and also different racial and ethnic populations. Other factors that influence low birth weight and preterm birth also need to be considered, they write.

Professor Gita Mishra, an expert in the field, added that this study shows that strategies to improve diets among women wanting to get pregnant are warranted. She added that these interventions may have long term health consequences.

She warned, "People born prematurely face a greater risk of metabolic and chronic diseases in adulthood, as well as poor cognitive development and academic performance."