Validity of pre-eclampsia registration in the medical birth registry of norway for women participating in the norwegian mother and child cohort study, 1999-2010.

Background: The Norwegian Mother and Child Cohort Study (MoBa), a prospective population-based pregnancy cohort, is a valuable database for studying causes of pre-eclampsia. Pre-eclampsia data in MoBa come from the Medical Birth Registry of Norway (MBRN); thus, we wanted to study the validity of MBRN pre-eclampsia registration for MoBa women.

Methods: We selected all MoBa pregnancies with pre-eclampsia registered in the MBRN (n = 4081) and a random control group (n = 2000) without pre-eclampsia registrations.

Folic acid supplementation and interpregnancy interval.

Background: Maternal folic acid supplementation between subsequent pregnancies may be important to reduce the risk of low folate status associated with short interpregnancy intervals. We examined how the prevalence of preconception folic acid use for a given pregnancy in Norwegian women varied according to the time interval from the previous pregnancy.

Methods: Analysis was based on 48 855 pairs of pregnancies with the second pregnancy included in the Norwegian Mother and Child Cohort Study (birth years 1999-2009).

Analysis of self-selection bias in a population-based cohort study of autism spectrum disorders.

Background: This study examined potential self-selection bias in a large pregnancy cohort by comparing exposure-outcome associations from the cohort to similar associations obtained from nationwide registry data. The outcome under study was specialist-confirmed diagnosis of autism spectrum disorders (ASDs).

Methods: The cohort sample (n = 89 836) was derived from the population-based prospective Norwegian Mother and Child Cohort Study and its substudy of ASDs, the Autism Birth Cohort (ABC) study.

Maternal active and passive smoking and hypertensive disorders of pregnancy: risk with trimester-specific exposures.

Background: The inverse association between prenatal smoking and preeclampsia is puzzling, given the increased risks of prematurity and low birthweight associated with both smoking and preeclampsia. We analyzed the Norwegian Mother and Child Birth Cohort (MoBa) to determine whether the associations varied by timing of prenatal smoking.

Methods: We conducted an analysis of 74,439 singleton pregnancies with completed second- and third- trimester questionnaires.

Self-selection and bias in a large prospective pregnancy cohort in Norway.

Self-selection in epidemiological studies may introduce selection bias and influence the validity of study results. To evaluate potential bias due to self-selection in a large prospective pregnancy cohort in Norway, the authors studied differences in prevalence estimates and association measures between study participants and all women giving birth in Norway. Women who agreed to participate in the Norwegian Mother and Child Cohort Study (43.