Seasonal Trends in Adolescent Pregnancy Conception Rates

STUDY OBJECTIVE: The objectives of this study were to determine if a seasonal trend exists in adolescent pregnancies and to compare the teen conception rate per month to an adult population. SETTING: The study was conducted in a tertiary care Canadian hospital that has a one-site model of care. DESIGN: A retrospective chart review of all adolescent pregnancies over a 5-year period (N = 838) was undertaken. From the 13,554 adult pregnancies over the same time period, a random sample of 838 pregnancies was chosen for similar chart review. A chi-square test was used to compare the proportion of pregnancies conceived in each calendar month between the two groups. PARTICIPANTS: Pregnancies ending in spontaneous abortions, elective terminations, ectopic pregnancies, as well as obstetrical deliveries, were included. RESULTS: There was a significantly different monthly trend seen in adolescent pregnancy conceptions when compared with the adult group (χ² = 24.38, df = 11, P = 0.0112). The adolescent group was observed to have a unique peak in the number of pregnancies conceived in March (10.5% of pregnancies conceived compared to 7.3% in adults). In addition, 8.5% of conceptions in adolescents occurred in December compared to 10.4% in adults. CONCLUSIONS: There are several plausible explanations for the modest but real differences identified in this study including trends in fecundity/fertility or social/school events that lead to increased sexual activity. Peaks in conception indicate times when a greater need for health care services exists, and when preventive education can be most effective.