Multiple Pregnancy: Causes, Risks, and How It Happens

Introduction

Multiple pregnancy occurs when a woman carries more than one fetus at the same time. It is also called a multiple birth and is becoming more common with rising maternal age and advancement in reproductive technologies. Many factors are identified as causes of multiple pregnancy, which include older age and assisted reproductive technologies.

Although having twins or multiple babies is often a cause of joy in families, it is essential to understand that it is a more complex and high-risk form of pregnancy compared to a singleton gestation (pregnancy with one baby). Women with multiple pregnancies require close monitoring because the physical demands on the mother’s body increase significantly, and this can lead to various complications for both the mother and the baby.

What is Multiple Pregnancy?

A multiple pregnancy happens when a woman is pregnant with more than one baby simultaneously. The most common is having twins (two babies), but some women may carry triplets (three babies) or Quadruplets (four babies), and so on. Anything over triplets is called a higher-order multiple pregnancy, which is usually quite rare.

A multiple pregnancy also carries a significant risk of complications such as preterm delivery, preeclampsia (or gestational hypertension), fetal growth restriction, anaemia, placental abruption, miscarriage, etc.

Types of Multiple Pregnancy

There are only two types of multiple pregnancy that can happen, and the difference between them goes back to how multiple pregnancy actually happens.

• Dizygotic Multiples (or fraternal twins) : Fraternal twins develop from different egg cells that are released by the ovaries at the same time and are simultaneously fertilised by different sperm cells. Because the eggs and sperm cells are different, such children are genetically distinct and can be of different genders.
• Monozygotic Multiples (or Identical twins) : Identical twins, on the other hand, develop from a single fertilised egg that splits into two or more embryos. Such twins are genetically similar and are always of the same gender.

In higher-order pregnancies, babies can be a mix of the above-mentioned types.

Risks and Complications of Multiple Pregnancy

1. Preterm Birth

Preterm birth is probably the most common complication of multiple pregnancy. Women with a multiple pregnancy are way more likely to go into early labour (before 37 weeks of pregnancy). The more babies you have inside you, the higher your risk of preterm or early birth.

Preterm babies are usually born with underdeveloped bodies and organs. They are often small, with low birth weight, and may have feeding and breathing problems. “Very preterm babies” is a term used for babies born under 28 weeks of pregnancy. In such babies, organs aren’t developed enough to sustain life outside the womb and thus require specialised care in a neonatal intensive care unit (NICU).

For many mothers, the goal is to complete all 37 weeks of pregnancy before delivery to ensure the baby's health.

2. Gestational hypertension and/or Preeclampsia

Women may develop high blood pressure disorders during pregnancy. Women carrying multiple babies are at twice the risk of developing high blood pressure during pregnancy in comparison to a singleton pregnancy.

3. Birth defects

In a multiple pregnancy, the risk of developing congenital problems is relatively higher than in normal pregnancies. These birth defects include neural tube defects and spina bifida.

4. Anaemia

Women with multiple births are also at an increased risk of developing low anaemia (low levels of healthy red blood cells).

Conclusion

Multiple pregnancies may bring immense joy to families. However, it is essential to understand the risks and complications associated with multiple pregnancy. Women with a “multiple pregnancy” need more support and help than they might imagine. Babies born from such pregnancies may also require specialised care if born earlier than 37 weeks.