Heavy prenatal alcohol exposure and obstetric and birth outcomes: a Danish nationwide cohort study from 1996 to 2018

Bibliographic Details

DOI 10.1016/s2468-2667(22)00263-8


Marcella Broccia; Bo Mølholm Hansen; Julie Marie Winckler; Thomas Larsen; Katrine Strandberg-Larsen; Christian Torp-Pedersen; Ulrik Schiøler Kesmodel



Heavy alcohol use during pregnancy can harm the fetus, but the relation to most obstetric outcomes remains unclear. We therefore aimed to describe maternal characteristics and estimate the association between heavy prenatal alcohol exposure and 22 adverse obstetric and birth outcomes.


We carried out a Danish nationwide register-based historical cohort study, including all singleton births from Jan 1, 1996, to Dec 31, 2018. Births of women who had emigrated to Denmark were excluded from the study due to missing data and women who migrated within 1 year before or during pregnancy were also excluded due to loss to follow-up. Data were extracted from the Danish Medical Birth Register, the Danish National Patient Registry, the Danish National Prescription Registry, the Danish Civil Registration System, and the Population Education Register. Logistic regression models were used to estimate crude and adjusted odds ratios (ORs) of obstetric and birth outcomes. Heavy alcohol use was defined by hospital contacts for alcohol-attributable diagnoses given to the mother, her infant, or both, or maternal redeemed prescriptions for drugs to treat alcohol dependence within 1 year before or during pregnancy.


Of 1 191 295 included births, 4823 (0·40%) were defined as heavily alcohol-exposed and 1 186 472 were categorised as a reference group with no identified heavy prenatal alcohol exposure. Heavy-alcohol-exposed births more often had mothers with psychiatric diagnoses (49·8% vs 9·6%), substance use (22·0% vs 0·4%), tobacco use (64·3% vs 15·8%), and low educational level (64·1% vs 17·6%) than did the reference group. For heavy-alcohol-exposed births, significantly increased adjusted ORs were found for small for gestational age (OR 2·20 [95% CI 1·97–2·45]), preterm birth (OR 1·32 [1·19–1·46]), haemorrhage in late pregnancy (OR 1·25 [1·05–1·49]), and preterm prelabour rupture of membranes (OR 1·18 [1·00–1·39]). Decreased adjusted ORs were found for postpartum haemorrhage (500–999 mL; OR 0·80 [95% CI 0·69–0·93]), gestational diabetes (OR 0·81 [0·67–0·99]), planned caesarean section (OR 0·82 [0·72–0·94]), pre-eclampsia and eclampsia (OR 0·83 [0·71–0·96]), and abnormalities of forces of labour (OR 0·92 [0·86–0·99]).


Heavy prenatal alcohol exposure is associated with adverse obstetric and birth outcomes and high proportions of maternal low educational level, psychiatric disease, and lifestyle risk behaviours. These findings highlight a need for holistic public health programmes and policy attention on improving pre-conceptional care and antenatal care.

Research in context

Evidence before this study

Alcohol can interfere with normal fetal development. Heavy alcohol drinking during pregnancy is associated with small for gestational age, low birthweight, preterm birth, and fetal death. Alcohol use during pregnancy is common in many countries, but the effect of heavy alcohol drinking on most obstetric outcomes and the related maternal characteristics are less clear. We searched PubMed from inception to Dec 13, 2021, for studies investigating the association between heavy prenatal alcohol exposure and obstetric and birth conditions. The search terms were “((pregnancy OR obstetrical OR neonatal) OR (pregnanc* OR obstetric* OR neonatal*)) AND (heavy AND alcohol)” with no language restrictions. The search generated 939 studies. The identified articles predominantly investigated the association between prenatal alcohol exposure and birth outcomes. Methodological heterogeneity among studies, design limitations such as recall bias, and a wide range of publication years were observed. Thus, the extent of obstetric and birth complications related to heavy alcohol exposure is uncertain and remains to be comprehensively studied with objective, large-scale data.

Added value of this study

We used Danish nationwide registries including more than 1·1 million births to describe maternal characteristics and the association between heavy prenatal alcohol exposure and obstetric and birth outcomes. This study provides new insight into the pattern of 22 adverse obstetric and birth outcomes. Most outcomes showed an uncertain association after adjustment; these were anaemia, Apgar score of less than 7 after 5 min, emergency caesarean section, forceps or vacuum delivery, haemorrhage in early pregnancy, liver disorders, perinatal mortality, placenta praevia, placental abruption, post-partum haemorrhage (>999 mL), retained placenta and membranes, stillbirth, and uterine rupture. Our findings provide important knowledge of the profile of pregnant women with heavy alcohol use and show a strong association with maternal psychiatric disease, substance use, and tobacco use.

Implications of all the available evidence

Heavy alcohol use during pregnancy is a high-risk behavior associated with maternal vulnerability and adverse obstetric and birth outcomes, which endanger both maternal and fetal health. The association between heavy alcohol exposure and both small for gestational age and preterm birth is marked, both of which are precursors of infant morbidity and mortality. Protecting maternal and children’s health begins pre-conceptionally. Heavy alcohol use during pregnancy and the associated risks require immediate action and persistent attention in antenatal planning, in addition to intervention at all levels.

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