Timing of elective delivery in twin pregnancies
Twins should be delivered before 38 weeks of gestation: AGAINST OD SAUGSTAD, PROFESSOR OF PAEDIATRICS, NORWAY
.................................................................................................................................................................. From 32 weeks of gestation twin pregnancies are, even in uncomplicated cases, associated with an increased risk of fetal death. Thus, the UK National Institute for Health and Clinical Excellence (NICE) has recommended the delivery of uncomplicated monochorionic (MC) twins at 36+0 and dichorionic (DC) twins at 37+0 weeks of gestation after a course of antenatal steroids (Visintin et al. BMJ 2011;343:d5714). Furthermore, the perinatal loss rate of MC twins between 32 and 36 weeks of gestation is two- to three-fold higher than DC twins, and the aetiology in each seem to differ. In MC twins the main causes of pregnancy loss is twin–twin transfusion and associated problems, whereas in DC twins growth restriction is most important. From the fetal perspective there are therefore good arguments to induce labour in uncomplicated dichorionic twins before 38 weeks of gestation; however, from the infant’s perspective this might not be the optimal timing. New information is accumulating regarding the morbidity and the mortality of so-called late preterm infants (those delivered between 34 and 36 weeks of gestation). Compared with term
ª 2014 Royal College of Obstetricians and Gynaecologists
deliveries these children have a higher incidence of respiratory diseases, including infections, and more often experience recurrent apnoea, temperature instability, jaundice, hypoglycaemia, feeding difficulties, sudden infant death syndrome, and delayed development. Length of stay and cost of hospitalisation are also increased for this category (Machado Jr et al. J Pediatr 2014;90:221–231). Even mortality as a young adult is increased in this group. The relative risk of total infant mortality for infants born between 34 and 36 weeks of gestation, compared with infants born at ≥37 weeks of gestation, is 2.9 (95% CI 2.8– 3.0) and 4.5 (95% CI 4.0–5.0) in the USA and Canada, respectively (Kramer et al. JAMA 2000;284:843–849). Few studies compare outcomes at 36 or 37 weeks of gestation with term infants; however, children born between 36 and 38.5 weeks were more likely to have a diagnosis of asthma at 6 years of age than infants born between 38.6 and 40.5 weeks of gestation (Raby et al. Pediatrics 2004;114:e327–e332). Randomised studies comparing elective birth at 37 weeks of gestation versus expectant management showed no difference
between the groups regarding perinatal death and infant outcomes; however, they were less likely to have a birthweight less than the third centile for gestational age and gender. The power of the study was low and no separate analysis for chorionicity was performed (Dodd et al. Cochrane Database Syst Rev 2014;2:CD003582). It seems clear that delivery before 38 weeks of gestation, and perhaps even before 39 weeks of gestation, increases both neonatal morbidity and mortality. DC twins, having a lower fetal loss rate than MC twins, may benefit from allowing later delivery (>38 weeks of gestation). A study of differences in outcomes between 36/37 and 38/39 weeks of gestation requires large numbers to achieve significance. In addition, the outcomes of MC and DC twins should be analysed separately. NICE emphasise that their present recommendations are based on evidence of low to moderate quality, and therefore more data are required to enable the timing of the optimal gestation for twin delivery to be discerned. Disclosure of interests None to declare. &
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Twins should be delivered before 38 weeks of gestation: AGAINST OD SAUGSTAD, PROFESSOR OF PAEDIATRICS, NORWAY
.................................................................................................................................................................. From 32 weeks of gestation twin pregnancies are, even in uncomplicated cases, associated with an increased risk of fetal death. Thus, the UK National Institute for Health and Clinical Excellence (NICE) has recommended the delivery of uncomplicated monochorionic (MC) twins at 36+0 and dichorionic (DC) twins at 37+0 weeks of gestation after a course of antenatal steroids (Visintin et al. BMJ 2011;343:d5714). Furthermore, the perinatal loss rate of MC twins between 32 and 36 weeks of gestation is two- to three-fold higher than DC twins, and the aetiology in each seem to differ. In MC twins the main causes of pregnancy loss is twin–twin transfusion and associated problems, whereas in DC twins growth restriction is most important. From the fetal perspective there are therefore good arguments to induce labour in uncomplicated dichorionic twins before 38 weeks of gestation; however, from the infant’s perspective this might not be the optimal timing. New information is accumulating regarding the morbidity and the mortality of so-called late preterm infants (those delivered between 34 and 36 weeks of gestation). Compared with term
ª 2014 Royal College of Obstetricians and Gynaecologists
deliveries these children have a higher incidence of respiratory diseases, including infections, and more often experience recurrent apnoea, temperature instability, jaundice, hypoglycaemia, feeding difficulties, sudden infant death syndrome, and delayed development. Length of stay and cost of hospitalisation are also increased for this category (Machado Jr et al. J Pediatr 2014;90:221–231). Even mortality as a young adult is increased in this group. The relative risk of total infant mortality for infants born between 34 and 36 weeks of gestation, compared with infants born at ≥37 weeks of gestation, is 2.9 (95% CI 2.8– 3.0) and 4.5 (95% CI 4.0–5.0) in the USA and Canada, respectively (Kramer et al. JAMA 2000;284:843–849). Few studies compare outcomes at 36 or 37 weeks of gestation with term infants; however, children born between 36 and 38.5 weeks were more likely to have a diagnosis of asthma at 6 years of age than infants born between 38.6 and 40.5 weeks of gestation (Raby et al. Pediatrics 2004;114:e327–e332). Randomised studies comparing elective birth at 37 weeks of gestation versus expectant management showed no difference
between the groups regarding perinatal death and infant outcomes; however, they were less likely to have a birthweight less than the third centile for gestational age and gender. The power of the study was low and no separate analysis for chorionicity was performed (Dodd et al. Cochrane Database Syst Rev 2014;2:CD003582). It seems clear that delivery before 38 weeks of gestation, and perhaps even before 39 weeks of gestation, increases both neonatal morbidity and mortality. DC twins, having a lower fetal loss rate than MC twins, may benefit from allowing later delivery (>38 weeks of gestation). A study of differences in outcomes between 36/37 and 38/39 weeks of gestation requires large numbers to achieve significance. In addition, the outcomes of MC and DC twins should be analysed separately. NICE emphasise that their present recommendations are based on evidence of low to moderate quality, and therefore more data are required to enable the timing of the optimal gestation for twin delivery to be discerned. Disclosure of interests None to declare. &
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