Risk of premature birth in multifetal pregnancy

Caesarean Section of Multifetal Pregnancy

Planned caesarean delivery (CD) did not significantly decrease or increase the risk of fetal or neonatal death or serious neonatal morbidity in twin pregnancy between 32 ^0/7 and 38 ^6/7 weeks of gestation, with the first twin in the vertex presentation. As prevalence rises for the second twin, emergency CD is necessary for delivery of the second twin after vaginal delivery of the first twin. Waiting after 38 weeks' gestation essentially requires close fetal and maternal surveillance to identify if those pregnancies may benefit to extend a gestational period. It is important to construct a system in which an emergency CD can be performed anytime. The caesarean section does not change in even multifetal pregnancy. Each step after laparotomy has few tips: (1) because the uterus strongly leans to the right, image the uterine rotation. To avoid thick vessels on the uterine lateral wall, perform long U -shaped incision using a scissor. 2) Ensure not to rupture the membrane of the second twin before delivery of the first twin. (3) Check the presentation of the second twin before rupture of that fetus's membrane. The second twin tends to change the presentation. If the upper uterine segment will clamp down and entrap the second twin, a vertical uterine incision is performed without hesitation. Women with multifetal pregnancy are at increased risk of postpartum hemorrhage (PPH). Mainly PPH is caused by uterine atony. Oxytocin should be prepared before starting the CD. All bleeding may not be recognized in the operation field. Do not lose the timing of blood transfusion.

Human uterine wall tension trajectories and the onset of parturition

Uterine wall tension is thought to be an important determinant of the onset of labor in pregnant women. We characterize human uterine wall tension using ultrasound from the second trimester of pregnancy until parturition and compare preterm, term and twin pregnancies. A total of 320 pregnant women were followed from first antenatal visit to delivery during the period 2000–2004 at the John Hunter Hospital, NSW, Australia. The uterine wall thickness, length, anterior-posterior diameter and transverse diameter were determined by serial ultrasounds. Subjects were divided into three groups: women with singleton pregnancies and spontaneous labor onset, either preterm or term and women with twin pregnancies. Intrauterine pressure results from the literature were combined with our data to form trajectories for uterine wall thickness, volume and tension for each woman using the prolate ellipsoid method and the groups were compared at 20, 25 and 30 weeks gestation. Uterine wall tension followed an exponential curve, with results increasing throughout pregnancy with the site of maximum tension on the anterior wall. For those delivering preterm, uterine wall thickness was increased compared with term. For twin pregnancies intrauterine volume was increased compared to singletons (), but wall thickness was not. There was no evidence for increased tension in those delivering preterm or those with twin gestations. These data are not consistent with a role for high uterine wall tension as a causal factor in preterm spontaneous labor in singleton or twin gestations. It seems likely that hormonal differences in multiple gestations are responsible for increased rates of preterm birth in this group rather than increased tension.

Neonatal nucleated red blood cell counts in twins

We counted nucleated red blood cells (NRBC) per 100 white blood cells (WBC) in the umbilical cord blood from 98 twins born to 49 women with uncomplicated twin pregnancies at > or = 34 weeks of gestation to better characterize NRBC in twins. Twelve women with monochorionic (MC) placentas and 37 with dichorionic (DC) placentas gave birth at 36.7 +/- .9 and 36.5 +/- 2 weeks of gestation, respectively. All twins were born with an Apgar score of > or = 7 at 1 min. Log10 (NRBC/100 BC) in 98 twins exhibited a nearly normal distribution, and was significantly associated with gestational age for both MC (r = -0.457, p = 0.025) and DC twins (r = - 0.275, p = 0.018), and with birth weight for both MC (r = -0.682, p < 0.001) and DC twins (r = -0.336, p = 0.003). Log10 (NRBC/100 WBC) tended to be larger in smaller twins than in larger twins in the MC group, and significantly larger in smaller twins than in larger twins in the DC group (p < 0.05). Intertwin difference in Log10 (NRBC/100 WBC) was defined as the value of Log10 (NRBC/100 WBC) of the smaller twin minus Log10 (NRBC/100 WBC) of the larger twin, and became greater with increasing intertwin difference in birth weight (r = 0.411, p = 0.003). These findings suggest that neonatal NRBC reflected gestational age and birth weight in twins. This preliminary observation using a small number of twins suggests that the smaller twin may have experienced a relative lack of oxygen compared with the larger twin in utero.