When a woman has two babies (foetuses) in her uterus, it is known as a twin pregnancy. Presently multiple births are reported more commonly than in earlier times owing to rise in the fertility treatments and progressing age of the mother. Almost 90% of the multiple births reported are twins.
Types of twins
Twins can be either
- Monozygotic(identical) or
- Dizygotic (fraternal or non-identical)
When a single ovum (egg) is fertilised by a single sperm and after fertilisation divides and results in the development of two foetuses with same genetic makeup, they are termed as identical twins.
Identical twins can also be classified based on the placenta and amniotic sac as:
- Monochorionic twins- Twins having a common placenta
- Monochorionic monoamniotic twins – Twins having a common placenta and amniotic sac
- Monochorionic diamniotic twins -Twins having a common placenta but different amniotic sacs
- Dichorionic twins- Twins having a single placenta and a single amniotic sac
When a woman releases two eggs in the same cycle which are fertilised by two separate sperm cells, then the resulting twins are different in their genetic composition and are non-identical (also known as fraternal twins).
They are more common and can be either male or female or both of the same sex.
All non-identical twins are dichorionic twins.
- Family history – If there is a maternal family history of twin pregnancy, then there are more chances of twin pregnancy
- The advanced age of the mother (>35 years)
- Assisted reproductive techniques (ART): Many eggs are released during ovulation due to stimulation by fertility drugs. During in vitro fertilisation, more than 1 fertilised ovum may be transferred. The incidence of multiple pregnancies is more in assisted reproductive techniques in comparison to natural conception, e.g., IVF (In-vitro fertilization (IVF) and Intracytoplasmic sperm injection (ICSI)
- Women of African or European descent are more prone for twin pregnancy
- Women who were previously on oral contraceptive pills and had recently discontinued them.
Twin pregnancies will mean some extra precautions which your doctor will recommend:
- With the progression of the pregnancy, you may be asked to cut down your physical activities, travel, and work.
- Occasionally, bed rest may be recommended to foster foetal development and decrease the risk of complications.
Complications with twin pregnancy are similar to the ones in normal pregnancy. Remember, a vast majority of twins are born healthy.
Complications can include:
- Premature birth: Twin pregnancies carry the risk of premature birth. Contact your doctor or go to the hospital in case you see signs of labour.
- Preeclampsia: Women carrying twins are at more risk of preeclampsia marked with high blood pressure and protein in the urine. Seek immediate medical attention on noticing any signs and symptoms of preeclampsia:
- Problems of the vision like blurred vision and flashes in front of eyes
- Abdominal pain
- A severe headache
- Swelling of feet, face, ankles and hands suddenly
- Weight gain due to retention of fluid
- Gestational Diabetes- You can have gestational diabetes ( increase in blood sugar levels seen during your pregnancy)
- Genetic defects– Due to a defect in some genes, the baby might be born with genetic defects
During twin pregnancy:
- Frequent checkups are needed to track the foetuses development and growth and monitor any signs of preterm labour.
- Nutrition: You need to focus on diet and supplements particularly protein, iron, folic acid, calcium, vitamins and essential nutrients in consultation with your physician.
- Weight gain: Gaining appropriate levels of weight can aid in the babies’ health.
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- Birth defects in monochorionic twins. Children’s Hospital of Wisconsin. Accessed 15 Mar. 16. http://www.chw.org/medical-care/fetal-concerns-center/conditions/infant-complications/birth-defects-in-monochorionic-twin/
- Pregnant with twins: what to expect. Baby Centre. Accessed 15 Mar. 16. http://www.babycentre.co.uk/a3787/pregnant-with-twins-what-to-expect
- Pregnant with twins. NHS Choices. Accessed 15 Mar. 16. http://www.nhs.uk/conditions/pregnancy-and-baby/pages/what-causes-twins.aspx
- Twins – identical and fraternal. Department of Health & Human Services, State Government of Victoria, Australia. Accessed 15 Mar. 16. https://www.betterhealth.vic.gov.au/health/conditionsandtreatments/twins-identical-and-fraternal