Consumption of alcohol during pregnancy - even in small amounts - expose women to 19% more risk of miscarriage as opposed to those who do not use alcohol, according to a new study by Vanderbilt researchers.
The study, published in Alcoholism: Clinical and Experimental Research, also found that for alcohol exposure of less than five drinks per week, each additional drink per week during pregnancy was associated with a 6% increase in miscarriage risk.
According to Alex Sundermann, an MD/PhD student at Vanderbilt University School of Medicine and the study's lead investigator, it is crucial to understand how consumption relates to miscarriage. She adds that "adverse pregnancy outcomes, like fetal alcohol syndrome, are often associated in popular culture with heavy consumption. However, our meta-analysis indicates even a modest amount of alcohol use has a meaningful impact on miscarriage risk."
The research shows that alcohol use increases oxidative stress for the fetus, causing cellular damage and ultimately miscarriage. A prior study from Sunderman's lab, led by Katherine Hartmann, MD, PhD, had found that more than half of women use alcohol in the early stages of pregnancy prior to having a positive pregnancy test, regardless of whether the pregnancy was planned.
Sundermann's most recent work involved a systematic review and meta-analysis of studies published between 1970 and 2019 about alcohol exposure and miscarriage. Twenty-four studies met the criteria for inclusion in the review, representing data from more than 231,000 pregnant women. The meta-analysis demonstrates exposure in pregnancy is associated with a dose-dependent increase in miscarriage risk. The systematic review also revealed important gaps in the existing literature, including a lack of knowledge about how the timing of alcohol exposure is linked to risk.
The prior study from Hartmann's lab found that most women stopped using alcohol when they first discover they are pregnant, but no studies account for the effect of this change in behaviour.
Sunderman added that the timing of alcohol exposure in pregnancy is important but not properly studied. The groundwork for fetal development is laid in those first weeks of gestation before pregnancy can be detected with a home test, and that is also the time when alcohol exposure is most prevalent. It's key that we understand the impact of consumption in those first weeks."
Sundermann hopes further investigation will help shed light on risk factors for miscarriage, which is experienced by one in three women. Despite being common, many women never receive answers about why their miscarriage occurred. Also, as for most pregnant women a healthy pregnancy is crucial, Sunderman wants to get this important information out there to empower women to make the best decisions.