TY - JOUR
T1 - Association of light-to-moderate alcohol drinking in pregnancy with preterm birth and birth weight
T2 - elucidating bias by pooling data from nine European cohorts
AU - Strandberg-Larsen, Katrine
AU - Poulsen, Gry
AU - Bech, Bodil Hammer
AU - Chatzi, Leda
AU - Cordier, Sylvaine
AU - Dale, Maria Teresa Grønning
AU - Fernandez, Marieta
AU - Henriksen, Tine Brink
AU - Jaddoe, Vincent W. V.
AU - Kogevinas, Manolis
AU - Kruithof, Claudia J.
AU - Lindhard, Morten Søndergaard
AU - Magnus, Per
AU - Nohr, Ellen Aagaard
AU - Richiardi, Lorenzo
AU - Rodriguez-Bernal, Clara L.
AU - Rouget, Florence
AU - Rusconi, Franca
AU - Vrijheid, Martine
AU - Nybo Andersen, Anne-Marie
PY - 2017/9
Y1 - 2017/9
N2 - Women who drink light-to-moderately during pregnancy have been observed to have lower risk of unfavourable pregnancy outcomes than abstainers. This has been suggested to be a result of bias. In a pooled sample, including 193 747 live-born singletons from nine European cohorts, we examined the associations between light-to-moderate drinking and preterm birth, birth weight, and small-for-gestational age in term born children (term SGA). To address potential sources of bias, we compared the associations from the total sample with a sub-sample restricted to first-time pregnant women who conceived within six months of trying, and examined whether the associations varied across calendar time. In the total sample, drinking up to around six drinks per week as compared to abstaining was associated with lower risk of preterm birth, whereas no significant associations were found for birth weight or term SGA. Drinking six or more drinks per week was associated with lower birth weight and higher risk of term SGA, but no increased risk of preterm birth. The analyses restricted to women without reproductive experience revealed similar results. Before 2000 approximately half of pregnant women drank alcohol. This decreased to 39% in 2000–2004, and 14% in 2005–2011. Before 2000, every additional drink was associated with reduced mean birth weight, whereas in 2005–2011, the mean birth weight increased with increasing intake. The period-specific associations between low-to-moderate drinking and birth weight, which also were observed for term SGA, are indicative of bias. It is impossible to distinguish if the bias is attributable to unmeasured confounding, which change over time or cohort heterogeneity.
AB - Women who drink light-to-moderately during pregnancy have been observed to have lower risk of unfavourable pregnancy outcomes than abstainers. This has been suggested to be a result of bias. In a pooled sample, including 193 747 live-born singletons from nine European cohorts, we examined the associations between light-to-moderate drinking and preterm birth, birth weight, and small-for-gestational age in term born children (term SGA). To address potential sources of bias, we compared the associations from the total sample with a sub-sample restricted to first-time pregnant women who conceived within six months of trying, and examined whether the associations varied across calendar time. In the total sample, drinking up to around six drinks per week as compared to abstaining was associated with lower risk of preterm birth, whereas no significant associations were found for birth weight or term SGA. Drinking six or more drinks per week was associated with lower birth weight and higher risk of term SGA, but no increased risk of preterm birth. The analyses restricted to women without reproductive experience revealed similar results. Before 2000 approximately half of pregnant women drank alcohol. This decreased to 39% in 2000–2004, and 14% in 2005–2011. Before 2000, every additional drink was associated with reduced mean birth weight, whereas in 2005–2011, the mean birth weight increased with increasing intake. The period-specific associations between low-to-moderate drinking and birth weight, which also were observed for term SGA, are indicative of bias. It is impossible to distinguish if the bias is attributable to unmeasured confounding, which change over time or cohort heterogeneity.
KW - Alcohol
KW - Birth weight
KW - Cohort study
KW - Confounding
KW - Preterm birth
KW - Small for gestational age
U2 - 10.1007/s10654-017-0323-2
DO - 10.1007/s10654-017-0323-2
M3 - Journal article
C2 - 29027084
VL - 32
SP - 751
EP - 764
JO - European Journal of Epidemiology
JF - European Journal of Epidemiology
SN - 0393-2990
IS - 9
ER -