Short summary

The detrimental effect of high doses of maternal alcohol intake during pregnancy seems settled. Therefore, total abstention is recommended in most current policies on alcohol intake in pregnancy. However, observational studies have found no indication of a harmful effect of low-moderate prenatal alcohol exposure when focusing on adverse pregnancy outcome or neuropsychological performance of the child. To minimize potential confounding we will study the association between average weekly alcohol intake and binge drinking in early pregnancy and preterm birth and low birth weight in a demographically homogenous and contemporary cohort.  

Rationale

Preterm birth often defined as <37 weeks gestation is identified as one of the most important factors associated with mortality and morbidity in infancy and early childhood. Preterm birth affects approximately 11% of all livebirths worldwide, though the prevalence deviates largely ranging from 5% in several European countries to 18% in some African countries. It has been documented that preterm infants have poorer outcomes including respiratory complications, infections, admission to neonatal intensive care units and re-hospitalization after discharge compared to term children. Similarly, is intrauterine growth retardation and low birth weight closely linked to the health outcome of the child.

The detrimental effect of high doses of maternal alcohol intake during pregnancy seems settled. However, a substantial number of observational studies have found no association between a low to moderate alcohol intake (often defined as >0 to 6 drinks/week) or episodic high alcohol consumption (binging) and preterm birth or low birth. Moreover, an average maternal alcohol intake up to 7-10 drinks/week in pregnancy has repeatedly been associated with a reduced risk of adverse pregnancy outcome when compared to abstainers . The majority of studies examining the associations are based on self-reported material collected prior to the new millennium, when official alcohol policies on alcohol in pregnancy were more liberal than currently. It is therefore plausible that the beneficial effect of prenatal alcohol exposure found in previous studies may be explained by a 'healthy-drinker-effect'.

We hypothesized that a potential confounding effect would be minimized by studying a demographically homogenous and contemporary cohort. Hence, in this study we examined the association between average weekly alcohol intake and binge drinking in early pregnancy and preterm birth and low birth weight in a cohort of pregnant women living in the uptake area of Copenhagen University Hospital, Denmark. 

Description of the cohort

The cohort consists of pregnant women referred for antenatal care at the obstetric department at Copenhagen University Hospital (October 2012 and October 2016). 

Data and biological material

Questionnaire data combined with data from the Danish Medical Birth Register.

Collaborating researchers and departments

Department of Gynecology and Obstetrics, Odense University Hospital and Institute of Clinical Research, University of Southern Denmark

• Professor Ellen Aagaard Nøhr, PhD, midwife

Department of Obstetrics, The Research Unit Women's and Children's Health, Juliane Marie Centre, Copenhagen University Hospital

• Senior reseacher Hanne Kristine Hegaard, PhD, midwife

Department of Obstetrics and Gynecology, Herlev University Hospital and Department of Clinical Medicine, University of Copenhagen

• Professor Ulrik Schiøler Kesmodel, PhD, MD

Department of Pediatrics (Intensive Care Neonatology), Perinatal Epidemiology Research Unit, Department of Pediatric and Adolescent Medicine, Aarhus University Hospital

• Professor Tine Brink Henriksen, PhD, MD