Adorable laughing ten-month old baby boy twins.
Adorable laughing ten-month old baby boy twins.

A twin refers to either of the two offsprings born during a single delivery. The twin may or may not closely resemble the other twin. Twins can be delivered through caesarean section or vaginally, though a caesarean delivery probability is higher. A vaginal delivery is possible if the baby first in line for delivery is head-down. As per research, approximately 20 percent pregnancies begin as multiples, but with time most of the additional fetuses stop developing and disintegrate and vanish instead. In some cases, one of the twins could get miscarried.

Gestation Period

The gestation period for a regular baby is 40 weeks. For twins (identical or non-identical), the period shortens by two weeks to around 38 weeks, resulting in preterm birth. Premature birth means lower birth weights and also increased health issues, such as jaundice. The shorter time period is courtesy the increasing toll on the pregnant woman’s body and the babies’ inability to acquire all essential nutrients. It’s also due to the limited size of a woman’s womb.


Twins can be categorized as identical twins (monozygotic) and non-identical twins (dizygotic or fraternal). Identical twins are formed when a fertilized ovum (egg) splits and makes two babies with identical genetic information. In case of non-identical twins, two ova (eggs) get fertilized by a couple of sperms and make genetically alike but non-resembling kids.

Immediately after birth, even identical twins may not look alike. A DNA test (involving blood samples, painlessly collected cheek cells or placentas) would help confirm the monozygotic relationship. At times, healthcare professionals may resort to ultrasound or membrane examination to identify the relationship.

Though rare, conjoined twins represent another twin variety. These are monozygotic twins with their bodies attached together at birth. Besides sharing biological membranes and placentas, conjoined twins also share organs and body parts. The linkage could be at any body part, but the point of attachment would be same for both. For instance, both will be linked at the head, abdomen, back, etc. and not abdomen-head, back-abdomen, etc.   

Usually, the twins split within the first few days post conception. When the split happens late, it could lead to a mono-mono twin pregnancy, which entails an umbilical cord entanglement. And if the division happens too late, the resulting twins are conjoined.

Factors Contributing to Twins

The following factors increase the likeliness of giving birth to twins:

  • Older mother: Women in their thirties and forties have higher estrogen production than younger women. This means the ovaries can produce multiple eggs simultaneously.
  • The higher the number of previous pregnancies, the greater the chances of conceiving twins.
  • Genes: If a woman is a twin herself, has previously given birth to twins, or has siblings with twins.
  • Ethnicity could play a role too. For instance, African women are likelier to give birth to twins than Asian women.
  • Medical treatment: Fertility treatments involving drugs or medical procedures (in-vitro fertilization).
  • Birth control pills, diet, and other factors that cause hyperovulation.

Detecting Twin Pregnancy

Detecting a twin pregnancy is possible with ultrasound, but it cannot tell whether it’s fraternal or identical during the initial stages. Twins could be diagnosed during the 12-week scan. If two sacs are visible, twins could be detected around the 6th week itself. By the 12th week, a mother comes to know if she is carrying fraternal or identical twins. At times, a twin pregnancy is suspected in case of an abnormally large womb.

Symptoms and Care

The signs and symptoms of a twin pregnancy are the same, but they may be in aggravated form. Also, extra care and precautions are required than regular pregnancy.

Women slated for twin pregnancy may feel intense or much earlier pregnancy signs. This is due to the higher human chorionic gonadotropin (hCG) levels in their body. Thanks to the twin pregnancy, frequent tests and ultrasound scans will be conducted to ensure proper growth, and diagnose and address complications (if any) at the earliest.        

Vitamins and minerals (diet element) intake would naturally have to be stepped up much further to meet the babies’ requirements. Iron (diet mineral) and folic acid could be prescribed to mitigate anemia and neural tube problems.


Generally, a twin pregnancy ends up in a healthy mother and babies. But there are exceptions.

  • Increased likelihood of high blood pressure in mothers.
  • Anemia in mothers.
  • Excessive fluid buildup (hydramnios) around the babies, resulting in preterm labor.

Increased miscarriage possibilities, thanks to higher chromosomal abnormalities risks.