Obstetrics and Gynecology - A.M. Gromova 2000

Multiple pregnancy
Labor course

The course of labour in a Multiple Pregnancy has its own distinct characteristics. The process begins with cervical dilation, rupture of the amniotic sac, and the delivery of the first fetus. This is followed by a pause in uterine activity lasting from 15 minutes to 1 hour, which is necessary for the uterine Muscles to adapt to the reduction in volume. Labour contractions then resume, leading to the rupture of the second amniotic sac and the delivery of the second twin. The interval between the birth of the First and Second twin is most commonly 20–30 minutes. Following the delivery of the second twin, the placentas detach and both sets of fetal membranes are expelled simultaneously.

However, this ideal course of labour is not always observed. Complications are quite frequent in multiple pregnancies. In 25–30% of cases, premature or early rupture of the amniotic membranes of the first fetus occurs, posing a significant risk to both mother and fetus regarding The Development of infection (chorioamnionitis, endometritis, intrauterine Pneumonia). Uterine inertia develops in 17–25% of cases, primarily due to the overstretching of the uterine musculature by the multiple gestational sacs. Another contributing factor is that the placental implantation site in a multiple pregnancy is considerably larger than in a singleton pregnancy, and the local effect of placental progesterone inhibits the contraction of the underlying myometrium. Furthermore, fetal malpresentations, preterm labour, and untimely rupture of the amniotic sac contribute to uterine inertia, which in turn leads to intrauterine Fetal Hypoxia. Prolonged labour causes maternal exhaustion, further suppressing uterine contractions, deteriorating the fetal condition, and necessitating obstetric intervention.

Following the delivery of the first fetus, in 3–7% of deliveries, premature detachment of a normally situated Placenta of the second twin occurs. This complication is life-threatening for both the mother and the unborn twin.

Another potential complication is a delayed rupture of the amniotic sac of the second twin.

After the birth of the first fetus, insufficient uterine Muscle retraction may occur, potentially causing a shift in the fetal lie from longitudinal to transverse, or vice versa.

During a multiple pregnancy, locked twins (collision) may occur during labour, which refers to their interlocking. This complication arises when the first fetus presents in the breech position while the second presents as cephalic. In such cases, embryotomy (fetal destructive surgery) becomes necessary.

The course of the Third Stage of labour in multiple pregnancies is frequently complicated by abnormalities in placental Separation, as well as hypotonic or atonic postpartum Hemorrhage, resulting from the impaired contractility of an overdistended Uterus. These factors also contribute to subinvolution of the uterus in the postpartum period and a higher incidence of postpartum infectious morbidity.

The development of twins born at term can be entirely normal; however, their birth weight is typically lower than that of infants from singleton pregnancies. Preterm twins generally exhibit signs of immaturity, leading to low resistance to infections, poor adaptation to the extrauterine environment, impaired nutrient absorption, and high morbidity. Consequently, the perinatal mortality rate for twins is 4 to 5 times higher than that of singleton pregnancies.