Background: Fibroids are benign smooth muscle tumours of the uterus common in women of reproductive age. The prevalence is thought to be higher amongst women over the age of 35 years and in African women. More women are delaying their child bearing leading to an increase in the number of women dealing with pregnancy in the context of fibroids. The relationship between pregnancy and fibroids is controversial. It is thought that pregnancy exerts a protective effect, an observation made from epidemiological and animal studies. Although the mechanism is not clear, the postpartum period is thought to possibly explain this benefit. There have been few studies on this effect and none focusing on a population of purely black African women. Study objective: To characterise prospectively the postpartum effect on uterine fibroid volume in black African women by comparing volumes in 3rd trimester and at the end of the pueperium. Design: A descriptive longitudinal sonographic study of fibroid volumes between 3rd trimester and at the end of the pueperium, using 2D ultrasound. Methods: The study setting was the Aga Khan University Hospital Nairobi Kenya, a private tertiary and teaching hospital. Pregnant black African women with uterine fibroids in their current pregnancy were enrolled into the study. They had a 2D ultrasound measurement of their fibroids in the third trimester (28-39 weeks) and a repeat at the end of the pueperium (median 6 weeks after delivery). The number, location and type of fibroid was indicated and volumes calculated using the formula; volume (ml) = 4/3 π a x b x c. Through a questionnaire, participants were asked about pregnancy and delivery complications, that is, pain, spotting, preterm labour, postpartum haemorrhage and preterm premature rupture of membranes. The primary outcome was the volume change over the study period and secondary outcomes were descriptions of patient and fibroid characteristics as well as pregnancy complications. Results: Data on 36 subjects with a mean age of 31.6 years were analysed. Taking a volume change of >10% to be significant, the study demonstrated that 83.33% (95% CI 71.15 - 95.51) of the fibroids reduced in size (P=<0.0001), out of which 8% were undetectable. There was no significant change in 8% and 8% showed an increase. Most fibroids were intramural (89%) followed by subserosal (11%). None of the participants had fibroids in other locations. Of the participants, 58% were primiparous and 42% were multiparous. Majority of the patients did