Stillbirth and large for gestational age at birth

Area of Science:

• Perinatal epidemiology
• Reproductive health
• Obstetrics

Background:

• A prior study suggested a link between large for gestational age (LGA) birth weight and stillbirth.
• Replication of this finding is crucial for understanding perinatal risks.
• Investigating potential confounding factors in the association between birth weight and stillbirth.

Purpose of the Study:

• To investigate the association between large for gestational age (LGA) birth weight and stillbirth.
• To determine if the previously reported association between LGA and stillbirth is reproducible.
• To explore the role of diabetes in the relationship between LGA and stillbirth.

Main Methods:

• Retrospective cohort study with nested case-control analyses using a Canadian perinatal database.
• Stillbirth defined as no signs of life at delivery ≥23 weeks gestation.
• Large for gestational age (LGA) defined using Canadian, American, and ultrasound norms.

Main Results:

• In adjusted analyses using population norms, large for gestational age (LGA) was not associated with stillbirth (OR 0.57).
• A significant interaction between pre-existing diabetes and LGA indicated increased stillbirth risk (OR 2.48).
• Case-control analysis showed LGA associated with stillbirth (OR 1.91) when using ultrasound norms and date-matched controls, but not when matched by gestational age (OR 0.98).

Conclusions:

• Large for gestational age (LGA) birth weight is not associated with stillbirth in the general population.
• The previously reported association between LGA and stillbirth may be an artifact of sampling strategy.
• LGA may elevate stillbirth risk in pregnancies complicated by pre-existing or gestational diabetes.