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Low birthweight repetition: coincidence or consequence?

To establish risk factors associated with Low Birthweight (LBW) recurrence, a historical cohort study was carried out among mothers enrolled in the 2004 Pelotas Birth Cohort. Data were collected by hospital-based interviews. Newborns were weighed and measured. Gestational age was defined according to the date of last menstrual period, ultra-sound scan before the 20th week of pregnancy or the Dubowitz method. Mothers who reported at least one LBW newborn on at least one of the two immediately previous pregnancies were included. A total of 4.558 births were identified in 2004, and 565 met inclusion criteria, out of which 86 (15.2%) repeated LBW in 2004. Among mothers with two LBW babies before 2004, 47.9% presented LBW recurrence. Prevalence ratios (PR) and 95% confidence intervals were estimated from Poisson Regression. Risk factors statistically associated to LBW repetition were: three or more gestations previously (PR=1.93); to give birth to a preterm baby previously (PR=4.01); female newborn in current gestation (PR=2.61) and intermediate or inadequate prenatal care quality (PR=2.57). Protective factors to LBW recurrence were: to belong to A/B economic classes (PR=0.89) and C (RP=0.25); and, to deliver a term baby in current gestation (PR=0.29). Identification of risk factors for this highly important outcome can help health services to establish strategies for the prevention of LBW recurrence.

Keywords: risk factors, low birthweight recurrence, preterm, prenatal care.

Risk factors for repetition of low birth weight, intrauterine growth retardation, and prematurity in subsequent pregnancies: a systematic review.

With the aim of collecting evidence on repetition of low birth weight, intra-uterine growth retardation (IUGR), and prematurity in successive pregnancies, a systematic review was conducted on MEDLINE, LILACS, PAHO, and MedCarib from 1965 to 2004, using as descriptors: “low birth weight and recurrence, repetition or previous�, “risk factors and repetition, recurrence or previous LBW�, “IUGR and recurrence, repetition or previous�, “risk factors and repetition, recurrence or previous IUGR�, “prematurity and recurrence, repetition or previous�, and “risk factors and repetition, recurrence or previous prematurity�. Of 24 studies, 18 were excluded due to inconsistency between the title and the actual subject investigated (obstetric history as a risk factor rather than a selection criterion). The most important risk factors associated with repetition of low birth weight were maternal age > 30 years, smoking, short inter-gestational interval, and black skin color; those associated with IUGR were maternal age < 20 or > 35 years, low maternal education, high blood pressure, drug addiction, and non-technical/non-professional paternal occupation; and with preterm birth, premature rupture of membranes, chorioamnionitis, preeclampsia, preterm labor, and inter-gestational interval less than 12 months. Low Birth Weight Infant; Fetal Growth Retardation; Premature Infant; Risk Factors

Tabagismo materno em sucessivas gestações e recorrência do baixo peso ao nascer

To evaluate the prevalence of maternal smoking in successive pregnancies and its association with repetition of low birth weight (LBW), a cross-sectional study was performed in a sample of women from the 2004 Birth Cohort in Pelotas, RS. Women with history of at least one LBW newborn in one of until two last pregnancies before the 2004 pregnancy were included. Of the 4458 births, 565 fitted the inclusion criteria. The prevalence of smoking during the present pregnancy was 32.4%. According to the prevalence of smoking during past pregnancies and in 2004, was observed that 67.1% of mothers have never smoked; 21.4% smoked in all pregnancies; 6.5% smoked during past pregnancies; and 5.0% smoked during the present pregnancy. In the adjusted analyses, no association between smoking in the present pregnancy and LBW newborns was found (PR=1.05; CI95% 0.62-1.80). Considering the prevalence of smoking in successive pregnancies, mothers which smoked during all pregnancies had a PR= 2.5 (CI95% 1.32-4.80) comparing to the ones which have never smoked. Smoking persistence during pregnancies is a very important factor to determine recurrence of LBW in successive pregnancies.

Key words: recurrence, low birth weight, smoking and successive pregnancies.