['To identify the contribution of the duration of the prenatal maternity leave on term delivery.', 'Characteristics of the prenatal maternity leave and delivery among 363 working women who had delivered a full-term infant at 1 of 4 hospitals in Montreal during 1996 were studied.', 'The presence of an intervention or complication during delivery was observed in 68.9% of the participants. The average duration of the prenatal maternity leave was about 8 weeks (SD = 7). The adjusted risk of a difficult delivery decreased significantly with the duration of the prenatal maternity leave (OR = 0.96; 95% CI: 0.93-0.99).'] Do [ Beneficial effect of maternity leave on delivery ]?