British journal of obstetrics and gynaecology最新文献

Objective To determine how first trimester detection rates for Down's Syndrome vary with maternal age and to calculate the predictive value of an increased risk report at various maternal ages.

Design Mathematical modelling of first trimester screening performance using fetal nuchal translucency and maternal serum free βhCG and pregnancy associated plasma protein-A (PAPP-A).

Methods From within the Gaussian distributions of each marker in normal pregnancies and those affected by Down's Syndrome a series of 15,000 marker multiple of the medians were obtained for each group. These markers were then used to calculate the risks of Down's Syndrome using maternal ages ranging from 15 to 49 and the background risk of Down's Syndrome at each age. Using a 1 in 300 risk cutoff (at time of sampling) the false positive rate and detection rate was assessed at each year of maternal age. The predictive value of a positive result was calculated using Baye's theorem.

Outcome measures False positive rates and detection rates at each year of maternal age between 15 and 49; the predictive value of a positive result for each maternal age between 15 and 49.

Results At 15 years of age the detection rate was 77% at a 1.9% false positive rate, 84% at a 4% false positive rate at age 30, rising to 100% at a 67% false positive rate at age 49. The probability of Down's Syndrome once identified with an increased risk was 1:34 at 15 years, 1:29 at 30 years and 1:6 at 49 years.

Conclusions As with second trimester biochemical screening, the detection rate and false positive rate vary considerably with age. However, detection rates across all ages are significantly higher than with second trimester screening. The risk of a positive screening result being a Down's pregnancy is considerably greater than with second trimester screening with an average probability of 1:29, compared with 1:55 in the second trimester. This information may be useful in counselling women with an increased risk result in first trimester screening.

Objective To assess the use of intrapartum defibulation for women who have had female genital mutilation.

Design A retrospective case analysis.

Setting King Abdulaziz University Hospital, a teaching hospital in Jeddah, Saudi Arabia.

Sample Two hundred and thirty-three Sudanese and 92 Somali women who were delivered at the hospital between January 1996 and December 1999.

Methods The outcome of labour of women with female genital mutilation who needed intrapartum defibulation were compared with the outcome of labour of women without female genital mutilation who did not need intrapartum defibulation.

Results One hundred and fifty-eight (48.6%) women had infibulation and needed intrapartum defibulation to deliver vaginally, 116 women (35.7%) did not have infibulation and gave birth vaginally without defibulation, and 51 (15.7%) women were delivered by caesarean section. There were no statistically significant differences, between women who underwent intrapartum defibulation and those who did not, in the duration of labour, rates of episiotomy and vaginal laceration, APGAR scores, blood loss and maternal stay in hospital. The surgical technique of intrapartum defibulation was easy and no intraoperative complications occurred.

Conclusions Intrapartum defibulation is simple and safe, but sensitivity to the cultural issues involved is essential. In the longer term, continuing efforts should be directed towards abandoning female genital mutilation altogether.

Objective To determine the incidence, risk factors, presentation, treatment and morbidity associated with secondary postpartum haemorrhage.

Design Analysis of 132 consecutive women presenting with secondary postpartum haemorrhage occurring over a three-year period.

Setting The maternity unit in a district general teaching hospital serving an annual delivery rate of around 6500 women.

Main outcome measures Factors associated with the cause of the haemorrhage and the resulting morbidity.

Results Most women presented during the second week after delivery. A history of primary postpartum haemorrhage (OR 9.3; 95% CI 6.2-14.0) and manual removal of placenta (OR 3.5; 95% CI 1.6-7.5) were the only significant risk factors identified. There was a high associated morbidity, with 84% requiring hospital admission, 63% surgical evacuation, 17% blood transfusion, with three women suffering a uterine perforation, one managed by hysterectomy. In women undergoing evacuation only, 37% had retained placental tissue confirmed after surgery; pre-operative ultrasound examination did not provide a better discrimination over clinical assessment for this finding.

Conclusions Secondary postpartum haemorrhage occurs in just under 1% of women, is associated with primary postpartum haemorrhage and retained placenta, and may result in significant maternal morbidity. This problem deserves more attention than it has received in recent years.

Objective 1. To measure blood gases and minute ventilation in healthy women with normal pregnancies, compare with non-pregnant women both at sea level and at high altitude; 2. to relate the results at altitude with duration of residence there.

Design Cross-sectional study.

Setting Antenatal clinics at sea level in Lima, Peru and at high altitude 4300m in Cerro de Pasco, Peru.

Population A total of 304 normal pregnant women between 7 and 41 weeks of gestation were studied, including 112 who lived at sea level and 192 at high altitude (4300m). For comparison 38 non-pregnant women (19 at sea level and 19 at high altitude) were also studied.

Methods Arterialised blood gases, haemoglobin, pulse oximetry and minute ventilation were measured once in each woman.

Main outcome measures PO₂, PCO₂, pH, haemoglobin, oxygen saturation, arterial oxygen content and minute ventilation and their relationship to gestation.

Results PO₂, PCO₂, bicarbonate, base excess and oxygen saturation were lower in pregnancies at high altitude compared with sea level; pH, haemoglobin, arterial oxygen content and minute ventilation were higher. At high altitude oxygen saturation and haemoglobin decreased towards term resulting in a fall in arterial oxygen content at the end of pregnancy. Women whose family had lived at high altitude for at least three generations maintained their oxygenation throughout pregnancy better than women whose family had lived there for less than three generations.

Conclusions In pregnancy at high altitude maternal adaptation appeared adequate in the first trimester but declined towards term. However, maternal oxygenation was maintained in those whose family had lived longest at high altitude suggesting a beneficial adaptation to a hypoxic environment, occurring over generations.

Objective To assess the relation of umbilical cord insertion and fusion of placentas with birthweight in monozygotic monochorionic, monozygotic dichorionic, and dizygotic twins.

Design A prospective population study.

Population 4529 liveborn twin pairs whose birthweight was recorded, placentas were examined, and site of umbilical cord insertion was determined after delivery.

Results Infants with a peripheral cord insertion weighed 150g less (P<0.001) than infants with a central cord insertion. Dizygotic infants had a significantly (P<0.001) higher incidence of central cord insertion (82%) than monozygotic dichorionic (65%) and monozygotic monochorionic (53%) infants. Monozygotic dichorionic infants with fused placentas and a peripheral cord insertion weighed on average 300g less (P<0.01) than infants with separate placentas and a central cord insertion. In dizygotic infants, fusion of the placentas did not affect birthweight.

Conclusions Umbilical cord insertion is associated with birthweight in all types of twins. Fusion of the placentas only affects the birthweight of monozygotic dichorionic, not that of dizygotic infants. This might be due to the greater proximity of implantation of monozygotic dichorionic twins. Dizygotic twins weighed more than monozygotic twins only when placentas were fused and cord insertion was peripheral. Hence, the difference between the mean birthweights of dizygotic, monozygotic dichorionic, and monozygotic monochorionic infants may originate from the least favourable antenatal situation, namely fused placentas with a peripheral cord insertion, which occurs most frequently in monozygotic twins.

Objectives To determine the effects of titrated oral misoprostol solution, compared with vaginal dinoprostone.

Study design Open, randomised clinical trial.

Setting Academic hospitals in South Africa and Liverpool, UK.

Methods Women undergoing induction of labour after 34 weeks of pregnancy were allocated by randomised, sealed opaque envelopes, to induction of labour with titrated oral misoprostol solution, or two doses of vaginal dinoprostone (2mg) administered six hours apart. Failure to deliver within 24 hours of randomisation was the primary outcome on which the sample size was based. The data were analysed by intention-to-treat.

Results Six hundred and ninety-five women were randomly allocated: 346 to oral misoprostol and 349 to vaginal dinoprostone. There were no significant differences in substantive outcomes. Vaginal delivery within 24 hours was not achieved in 38% of women in the oral misoprostol group and 36% in the vaginal dinoprostone group (RR 1.08; 95% CI 0.89-1.31). The caesarean section rates were 16% and 20%, respectively (RR 0.80; 95% CI 0.58-1.11). Hyperstimulation with fetal heart rate changes occurred in 4% of women in the oral misoprostol group and 3% after vaginal dinoprostone (RR 1.32, 95% CI 0.59–2.98). The response to induction of labour in women with unfavourable cervices was somewhat slower with misoprostol when membranes were intact, and with dinoprostone when membranes were ruptured. There were no differences in neonatal outcome between the two groups.

Conclusions This new approach to oral misoprostol administration was successful in minimising the risk of uterine hyperstimulation, which has been a feature of misoprostol use for induction of labour, at the expense of a somewhat slower response in women with intact membranes and unfavourable cervices. Misoprostol is not registered for use in pregnant women, and further research is needed to confirm optimal and safe dosages.

Objective To determine whether the higher levels of obstetric intervention and maternity service use among older women can be explained by obstetric complications.

Design A retrospective analysis of routinely collected data from the Aberdeen Maternity and Neonatal Databank.

Participants All residents of Aberdeen city district delivering singleton infants at the Maternity Hospital 1988-1997 (28,484 deliveries).

Main outcome measures Odds ratios for each intervention in older maternal age groups compared with women aged 20-29. Interventions considered include obstetric interventions (induction of labour, augmentation, epidural use, assisted delivery, caesarean section) and raised maternity service use (more than two prenatal scans, amniocentesis, antenatal admission to hospital, admission at delivery of more than five days, infant resuscitation, and admission to the neonatal unit).

Methods Logistic regression was used to investigate the association between maternal age and the incidence of interventions. The odds ratios for each intervention were then adjusted for relevant obstetric complications and maternal socio-demographic characteristics.

Results Levels of amniocentesis, caesarean section, assisted delivery, induction, and augmentation (in primiparae) are all higher among older women. Maternity service use also increases significantly with age: older women are more likely to have an antenatal admission, more than two scans, a hospital stay at delivery of more than five days, and have their baby admitted to a neonatal unit. Controlling for relevant obstetric complications reveals several examples of effect modification, but does not eliminate the age effect for most interventions in most groups of women.

Conclusions Higher levels of intervention among older women are not explained by the obstetric complications we considered.