Familial patterns in birth characteristics: impact on individual and population risks

Area of Science:

• Reproductive Epidemiology
• Perinatal Health
• Genetics and Birth Outcomes

Background:

• Previous studies suggested familial patterns in reproductive outcomes.
• Few studies comprehensively evaluated both gestation length and types of growth retardation.

Purpose of the Study:

• To evaluate familial trends in preterm deliveries and small-for-gestational age (SGA) births.
• To assess the recurrence of specific growth retardation patterns in consecutive deliveries.
• To investigate the influence of maternal birth characteristics and sibling delivery history on reproductive outcomes.

Main Methods:

• Utilized a Swedish cohort of women born 1955-1972, linked to their reproductive experiences (1973-1990).
• Analyzed familial trends in preterm deliveries, SGA births, and two types of growth retardation.
• Employed logistic regression to calculate adjusted relative risks (RR) for various familial comparisons.

Main Results:

• Mothers born small-for-gestational age (SGA) had a ~50% higher risk of delivering preterm or SGA infants.
• Recurrence of preterm delivery (RR=3.7) and SGA delivery (RR=7.8) was significantly higher in subsequent pregnancies.
• Maternal history of a preterm birth increased the risk of delivering a preterm infant by 80%; chronic growth retardation was more recurrent than acute.

Conclusions:

• Demonstrated familial trends in gestational age and birth body proportions.
• Highlighted the role of maternal birth characteristics and sibling history in reproductive outcomes.
• Discussed the population attributable risk percentages within the Swedish context.