RESUMO
The study aspired to assess the impact of time of birth on spontaneous onset of labour and delivery. A retrospective descriptive study was conducted from the Empangeni Hospital delivery registry on 9;397 infant births between January to December 2005; weighing more than 1;000 g. Logistic regression; adjusting for birth weight and for gender was used to estimate the relationship between spontaneous birth and timing of birth. A higher proportion of births (59) occurred between 10h00 and 22h00 of the day. Estimating the hourly births; we found that the daytime peak is 5.3and occurred at 10h00 while the night-time peak is 4.9and occurred at 20h00. Maternal age was significantly associated with the timing of spontaneous births (p 0.05). A higher proportion of preterm babies was born during the day (6.4) and early night (3.4) compared to late night births (1.6). There were significant differences between multiple births and low birth weight infants born during the day (1.1; 6.9) and night (0.8; 6.3). However; low birth weight babies were born mostly during early night rather than late night (4vs. 2.3; p 0.05). Adverse pregnancy outcome; measured by estimating the perinatal mortality rate; was the same for day and night and was equally distributed between early and late night. Timing of birth of infants did not influence the negative outcomes of pregnancy among this study population