SummaryActivated protein C (APC) resistance, due to a point mutation in the factor V gene (FV:Q506), is a major risk factor for venous thromboembolism. To determine the prevalence of APC resistance in a large series of pregnant women, and to elucidate its obstetric consequences, we performed a prospective study in Malmö, Sweden, comprising 2,480 women enrolled in early pregnancy. The presence of APC resistance (the FV:Q506 allele) was determined. The women were interviewed about their medical histories including venous thromboembolic events (VTE) in relatives. The outcome variables were the VTE rate, intrapartum blood loss, and the prevalence of selected pregnancy complications such as fetal loss, pre-eclampsia, and intrauterine growth retardation.The overall prevalence of APC resistance was 11% (270/2480). The APC-resistant subgroup did not differ significantly from the non-APC-resistant subgroup in terms of pregnancy complications, but was characterized by an 8-fold higher risk of VTE (3/270 vs. 3/2210), a lower rate of profuse intrapartum haemorrhage (3.7% vs. 7.9%) (p = 0.02), and less intrapartum blood loss (340 ml vs. 361 ml) (p = 0.04). Despite the high prevalence of APC resistance in this series of gravidae (11%), its presence was unrelated to adverse pregnancy outcome apart from an 8-fold increased risk of VTE.

222 consecutive fetuses found by ultrasound to be in breech presentation in the 33rd gestational week were followed with repeated examinations in weeks 35 and 38. Ninety-one of these fetuses persisted in breech presentation until delivery, while cephalic version occurred in 131. The frequency of hip joint instability was 21% in the breech delivered group and 1.5% in the vertex delivered group. The position of the fetal legs was established at each ultrasound examination. The intrauterine fetal attitude was classified as extended when the fetuses had extended knees and maximally flexed hips at all ultrasound examinations. This occurred in 30 breech delivered fetuses, 47% of which developed hip joint instability. Only 8% of the breech born infants with flexed legs in utero developed hip joint instability. It is concluded that instability of the hip joint is a consequence of the intrauterine attitude, rather than of the breech delivery per se.

225 fetuses with ultrasonically determined gestational age were shown by ultrasound to be in breech presentation in the 33rd gestational week. The biparietal diameter (BPD) and the mean of two perpendicular abdominal diameters (AD) were measured ultrasonically in gestational weeks 33, 35, and 38. Based on these measurements, fetal weight was estimated and compared with weight, length, and head circumference at birth and at 18 months of age. 42% of the fetuses were born in breech presentation (breech group) and 58% in vertex presentation (vertex group). The mean birth weight corrected for gestational age was 4.9% lower in the breech group than in the vertex group, which corresponds to the lower intra-uterine values of BPD and AD found in the breech group. The weight differences at birth still persisted at 18 months of age. There were no differences between the groups regarding head circumference or length, either at birth or at 18 months of age.

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Umbilical cord acid-base state and Apgar score were compared in neonates after breech and vertex term birth. The breech group comprised 149 consecutive newborns, 91 born vaginally and 58 by cesarean section. The control group consisted of a random sample of 150 newborns in vertex presentation: 100 born vaginally and 50 by cesarean section. Among vaginally born babies, the 1-min Apgar score was more often depressed in the breech presentation group than in the vertex group; after 5 min the Apgar scores were comparable in both groups. No difference was found in umbilical cord values of pH and base excess between the breech and the vertex groups when comparison was made within each delivery mode. In both greups, umbilical cord values were lower after vaginal than after abdominal delivery. It is concluded that in selected cases, uneventful vaginal breech labor and delivery at term is not associated with an increased risk of asphyxia.