The impact of the interpregnancy interval on birth weight and other pregnancy outcomes O impacto do intervalo entre gestações no peso de recém-nascidos e outros desfechos da gravidez

Objectives: to investigate the relationship between the interpregnancy interval and low birth weight and other pregnancy outcomes. Methods: this case-control study was carried out in hospitals from January 2010 to April 2011. For cases, mothers of 1216 newborns with birth weight <2500 g were approached and 854 mothers participated (70.2%). For controls, mothers of 1158 newborns with E2500 g were approached and 854 mothers participated in this study (73.7%). Face-toface interviews were conducted to complete the questionnaires. Results: of the newborn babies with low birth weight, the risk was higher among mothers with a short interpregnancy interval (40.3%), whereas for infants with normal birth weight, the majority of the mothers had a longer interpregnancy interval of 24 months (44.7%). A short interpregnancy interval of 612 months was more common among women of <25 years (49.4%; p<0.001) and those who were illiterate (13.1%; p=0.043) with a higher risk of low birth weight compared to the controls. Prenatal care during the 1st trimester was lower in women with low birth weight children (p<0.001). Normal delivery was observed less in women with a short birth interval among cases (58.7%) compared to controls (79%) (p=0.001). A J-shaped association was observed between low birth weight and the interpregnancy interval.