Objectives: Global estimates of maternal and perinatal mortality have remained unchanged over the past 20 years, and strategies are being sought to decrease the occurrence of maternal and perinatal death. The objective of this study was to evaluate the association between inter-pregnancy interval and the occurrence of adverse maternal and perinatal outcomes.
Design and setting: Cross-sectional study of the obstetrical and perinatal records in an intra-hospital obstetrics database between 1986 and 2000 at a tertiary maternity hospital in Brazil.
Participants: A total of 14,930 records of parous women who delivered singleton infants.
Main outcome measures: Crude and adjusted odds ratio estimates of gestational outcome according to inter-pregnancy intervals.
Results: During the period of the study, 34.6% of records referred to women with an inter-pregnancy interval <18 months. After the adjustment performed for 11 confounding factors and assuming an inter-pregnancy interval of 18-23 months as reference, short intervals (<6 months) were observed to be associated with a greater risk of low birth weight (odds ratio: 1.74; 95% confidence interval: 1.18-2.55), and preterm birth (1.56; 1.01-2.46). On the other hand, long intervals were significantly associated with fewer C-sections (0.69; 0.56-0.82), and a greater risk of premature rupture of membranes (PROM) (1.57; 1.20-2.06) and low birth weight (1.46; 1.03-2.06).
Conclusions: Short inter-pregnancy intervals are associated with a higher risk of low birth weight and preterm birth, while long intervals are associated with a higher risk of PROM, low birth weight and a lower risk of C-section.