Fetal Medicine - FAQs

How does twin pregnancy occur?

When two sperms fertilize two eggs, two embryos are formed who have their own placentas (afterbirth). These non-identical or ‘fraternal’ twins constitute 80% of twin pregnancies and are called dichorionic diamniotic (DCDA) twins. When one sperm fertil¬izes an egg which divides into two later on, identical twins or monochorionic twins are formed. These are the rarer variety where the twins are of the same sex, have the same genetic makeup and share the same placenta.

How is twin pregnancy diagnosed?

The diagnosis of twin pregnancy is confirmed on ultrasound.

What are the risks associated with twin pregnancy?

Most twin pregnancies will have an uneventful course and normal delivery; however it is important to be aware of the following complications:


Since there is increased demand for nutrients for two babies rather than one, there is increased risk of developing anemia and other nutritional deficiencies.

High blood pressure:

Mothers with multiple pregnancy have a higher chance of developing high blood pressure in pregnancy.

Premature delivery:

Since the womb is getting over distended with more babies than one, almost 50% twins will deliver earlier than 37 weeks and have lower birth weights than an average singleton. Almost one in ten will deliver before 32 weeks of pregnancy.

Operative delivery:

There is a higher chance of instrumental vaginal delivery or caesarean delivery in twin pregnancy.

What does it mean for the mom?

The mother may have more pronounced minor side effects of pregnancy like morning sickness, abdominal heaviness, mechanical difficulties due to the larger size of the womb, more swelling of the feet etc.

More frequent hospital visits and more frequent ultrasound scans: An expectant mother with twin pregnancy would need more frequent hospital visits and more frequent checkups than their singleton counterparts.

What are the risks to my babies?

Dichorionic or non-identical twins:

There is a high chance of preterm delivery, growth restriction and low birth weight (2.5 kg) in twin pregnancy. Preterm infants are at risk of lung im¬maturity, infection, intestinal problems and require prolonged hospital stay.

Monochorionic or identical twins:

In addition to above risks, there is a small increased risk of birth defects in identical twins. They are also at risk of complications arising from unequal sharing of the placenta which include differential growth patterns, twin to twin transfusion syndrome (TTTS), acardiac twinning and even death of a single baby leading to neurological complications in the surviving twin.

Should care be modified for a mother with twin pregnancy?

Yes, a mother with twin pregnancy needs more specialised care and intensive monitoring for ensuring both maternal and fetal wellbeing and for early detection of complications. This would mean more frequent hospital visits, more investigations and more frequent ultrasound scans. An obstetrician experienced in managing high risk pregnancy and Fetal Medicine specialist should be involved in the care of these mothers. You should deliver in a tertiary care hospital with neonatal intensive care (NICU) facilities.

Plan of antenatal care for twin pregnancy at Apollo Centre for Fetal Medicine

First trimester screening:

All twin pregnancies should first be seen at around 12 weeks. An ultrasound at this time helps in assigning the ‘chorionicity’ which is the single most important factor in determining prognosis and directing further management. At the same time, this scan helps in detection of chromosomal abnormalities like Down’s syndrome and certain other birth defects in either of the twin.

A fetal anomaly scan is done at 18 to 20 weeks to detect structural abnormalities in either baby.

At each visit, the mother’s blood pressure is checked and urine tested for proteins.

Dichorionic (DCDA) twin pregnancy:

Further growth scans or fetal well being scans are done at four weekly intervals, ie approximately at 24, 28, 32 and 36 weeks respectively.

Monocorionic (MCDA) twin pregnancy:

Monocorionic pregnancies are followed at 2 weekly intervals, i.e. at 16, 18, 20, 22, 24, 26, 28, 32, 34 and 36 weeks.