Is alcohol exposure before and during pregnancy associated with reduced longitudinal fetal growth?

By Dr. Chinta SidharthanReviewed by Lily Ramsey, LLMAug 29 2023

In a recent study published in BMC Medicine, researchers examined the association between exposure to alcohol in the periconceptional and prenatal periods and longitudinal growth of the fetus, focusing on the quantity and timing of alcohol consumption.

Study: Alcohol exposure before and during pregnancy is associated with reduced fetal growth: the Safe Passage Study. Image Credit: AfricaStudio/Shutterstock.com

Background

Despite widespread efforts worldwide to spread awareness about the dangers of prenatal alcohol exposure, the prevalence of alcohol consumption among pregnant individuals across the globe is 10%.

The prevalence of prenatal alcohol consumption also varies across regions and countries, with the eastern Mediterranean region having the lowest average consumption and European countries having the highest average prenatal alcohol consumption. In some regions of South Africa, alcohol consumption among pregnant individuals is known to be as high as 38%.

Maternal alcohol exposure is known to cause fetal alcohol spectrum disorders (FASD), which results in a wide range of somatic anomalies, craniofacial abnormalities, and neurodevelopmental disabilities.

The diffusion of alcohol from the mother to the fetus through the placenta also results in the accumulation of alcohol in the amniotic fluid, resulting in prolonged alcohol exposure to the fetus.

However, while considerable research has been conducted on the impact of prenatal alcohol exposure on fetal development, very few studies have longitudinally or quantitatively assessed the association between fetal growth and alcohol consumption in pregnant individuals.

About the study

In the present study, the researchers examined data from the Safe Passage Study, which included a prospective cohort of 12,000 expectant mothers from specific communities with high prenatal alcohol consumption risk in the United States (U.S.) and South Africa.

The data included in the present study only examined the South African cohort. They evaluated prenatal alcohol exposure longitudinally as a continuous variable, emphasizing the quantity and timing of alcohol exposure.

Additional data was collected for a subset of randomly selected participants from the original cohort. These participants were enrolled in the study before six months of gestation, with follow-up visits between gestation stages of 20 and 24 weeks, 28 and 32 weeks, and after 34 weeks.

Women with incomplete ultrasound results and non-continuous follow-ups were excluded, as were pregnancies with other complications unrelated to alcohol consumption, such as stillbirths, miscarriages, congenital abnormalities, and twin pregnancies.

Interviews were conducted to collect information on alcohol consumption. They were classified according to the timing of alcohol consumption as during the preconception stage, 15 days before or after the last menstrual event, and during the first, second, or third trimesters. Information on maternal alcohol consumption and tobacco use was also collected during each follow-up prenatal visit.

Fetal growth measurements were obtained from progressive ultrasound images, including head circumference, biparietal diameter, abdominal circumference, and femur length.

These measures were also used to estimate fetal weight. Factors such as maternal age, medical and obstetric history, educational qualifications, income, and parity were recorded as potential covariates.

Information on maternal anxiety and depression, upper-arm circumference, and self-reported use of substances such as methamphetamines or marijuana was also collected.

Results

The results indicated that alcohol consumption during the prenatal period has a negative impact on fetal growth, especially when alcohol consumption occurs in the preconception stage or during the second trimester.

Accumulative alcohol exposure was linked to decreased growth of the fetal abdomen and femur and an overall lower birth weight.

While alcohol consumption during the second trimester and the preconception period were linked to lower fetal and birth weight estimates, prenatal alcohol exposure during the third trimester was associated with an increase in birth weight.

However, lower femur growth was also seen in cases of prenatal alcohol exposure during the third trimester. Additionally, the use of tobacco along with alcohol consumption was also associated with a decrease in fetal femur growth.

Surprisingly, binge drinking, which was defined as consumption of greater than four portions of alcohol per occasion, did not show additional associations with impaired fetal growth.

The incidence of depression was also found to be close to 50% in the study population, and the researchers believe that it is correlated to the socio-economic status of the women in the study since they experience high levels of unemployment and poverty in the region.

Additionally, the researchers discussed some possible mechanisms that could explain the correlation between prenatal exposure to alcohol and impaired fetal growth, including the impact of alcohol on cellular proliferation and the involvement of genetic factors in growth deficiencies due to alcohol exposure.

Conclusions

Overall, the findings indicated that the timing and quantity of alcohol exposure during the prenatal stage did impact fetal growth, with exposure during the second trimester and the preconception period resulting in the impaired development of the fetal abdomen and femur and decreased birth weight.

These results further emphasize the need to educate expectant mothers and those attempting to conceive about the impact of alcohol consumption on the health and development of their fetuses.