Multiple pregnancies occur when more than one fetus develops in the uterus. Understanding how they form depends on two main factors: zygosity and placentation. Zygosity refers to the genetic makeup of the babies. Dizygotic twins, commonly called fraternal twins, develop from two separate eggs fertilized by two separate sperm. They can be of the same or different sexes and are no more genetically alike than ordinary siblings. Monozygotic twins, or identical twins, arise from a single fertilized ovum that splits into two embryos. They share the same genetic material and are always of the same sex.
Placentation describes how many placentas and amniotic sacs the fetuses share. This is critical for midwifery management because shared placentas carry higher clinical risks.
Suspecting and confirming a multiple pregnancy early ensures proper antenatal care in Nigerian health facilities. Midwives must rely on a combination of clinical suspicion and diagnostic tools.
Clinical signs often provide the first clue. A pregnant woman may report uterine size that feels dates-plus (larger than expected for her gestational age), excessive weight gain, severe early morning sickness due to high hormone levels, or feeling fetal movements in multiple distinct quadrants simultaneously. Physical examination may reveal a uterine fundal height measuring more than 4 centimeters above the expected height for gestational age, multiple fetal poles upon palpation, or hearing more than one distinct fetal heart rate.
Definitive diagnosis, however, relies entirely on ultrasound scanning. Early first-trimester ultrasound is the gold standard because it not only confirms the presence of multiple embryos but also accurately maps out the chorionicity and amnionicity by visualizing membrane thickness and dividing partitions.
Managing a multiple pregnancy requires increased frequency of antenatal visits and specialized nutritional support. The physiological burden on the mother is vastly increased, raising the risk of anemia, pregnancy-induced hypertension, and gestational diabetes.
Nutritional demands are significantly higher. Midwives must counsel mothers to increase their daily intake of calories, proteins, iron, and folic acid to support the growth of more than one fetus and prevent severe maternal nutritional depletion.
Surveillance schedules must be tight. Monochorionic pregnancies require serial ultrasound scans every two weeks starting from around sixteen weeks to monitor for early signs of twin-to-twin transfusion syndrome (TTTS) and selective fetal growth restriction. Dichorionic pregnancies are scanned less frequently, typically every four weeks, to check normal growth trajectories and amniotic fluid volumes.
Multiple pregnancies carry a substantially elevated risk of complications for both mother and babies. Midwives must remain vigilant throughout the antenatal and intrapartum periods to recognize these issues early.
The mode of delivery for a multiple pregnancy depends on chorionicity, fetal presentations, gestational age, and the overall clinical condition of the mother and fetuses. Preparation requires a multidisciplinary team including obstetricians, midwives, anesthetists, and pediatricians.
For twin pregnancies, vaginal delivery may be safely attempted if the first twin is presenting by the vertex (head-first). If the first twin is breech, a caesarean section is typically performed to prevent locked twins or head entrapment. When the first twin is delivered vaginally, the midwife and obstetrician must manage the second twin carefully. Monitoring fetal heart rate immediately after the first birth is essential. The presentation of the second twin is assessed, and if necessary, internal or external version may be performed, or assisted breech extraction initiated, provided there is no excessive delay between the births.
Triplets and higher-order multiples are almost universally delivered via planned elective caesarean section due to the extreme risks of intrapartum complications and malpresentations.