How twins are conceived

Even to those who already have twins, how twins are conceived remains a topic of awe. Excitement, uncertainty and disbelief are common feelings among parents who learn they are expecting twins.

It is even more awesome when an ultrasound scan was not done and the existence of the twins is unknown until birth. Some women are overwhelmed, and shudder at the thought of having more than one baby in their arms. Meanwhile, many marvel at the occurrence of a multiple pregnancy, and how it happens.

How multiple pregnancies occur

Multiple births are grouped into two:

• Fraternal Twins: Occurs when two eggs are fertilised by two different sperm, and implant in the uterus resulting in fraternal twins. Such twins have similarities among themselves, though in the womb each foetus has a placenta, and amniotic sac (the membrane holding the amniotic fluid, within which the foetus is held).
• Identical Twins: A single egg is fertilised by a single sperm, and the fertilised embryo splits into two- to form identical twins of either boys or girls.

What causes multiple pregnancies?

A multiple pregnancy occurs either as a result of natural or reproductive technological factors.

Natural factors

Due to financial, professional and personal reasons, some women delay giving birth till very late. For example at the age of above 35. At this age, chances of a woman getting a multiple pregnancy are higher. Older women are more likely to produce more than one egg per menstrual cycle. If two eggs are produced per cycle,  there is a higher likelihood of having fraternal twins.

Technological factors

Assisted reproductive technologies like in vitro fertilisation (IVF) help many couples to conceive. IVF includes medications that stimulate ovulation, resulting in multiple eggs being produced and then fertilsed.  Examples of these medicines include; clomiphene citrate and follicle stimulating hormone.

Can you tell you have a multiple pregnancy?

Yes, there are signs that indicate you may be having a multiple pregnancy. It is very important that you know whether you are going to have one baby or more. This will enable you take precautions in avoiding pregnancy and birth complications, or to choose the right birth method to deliver your babies safely. You can tell you have a multiple pregnancy:

• If the uterus appears larger than expected
• If you have persistent, recurring and exaggerated morning sickness
• When you experience frequent hunger pangs
• If you gain excessive weight
• When you feel as if there are foetal movements, at different parts of the abdomen at the same time.

The standard way of confirming a multiple pregnancy is through an ultrasound scan. This uses sound waves to project images of blood vessels, tissues and organs to the computer. It is normally easy to tell from the screen, if there is more than one baby in the womb.

Do Multiple Pregnancies Cause More Risks?

Did you know that women expecting twins or more babies, face a higher risk of birth complications? Experience indicates that multiple birth pregnancies, as they are commonly known in medical circles, pose the following twin pregnancy risks / dangers to either the mother or the babies:

1. Premature/preterm labour or birth

Multiple pregnancies often end earlier than single birth pregnancies. The result is that the babies are born before all their organs develop fully. They usually have low birth weight, and on many occasions require aided breathing and feeding. Such babies need additional care after delivery, but unless they have any other complications they grow well.

2. Pregnancy-induced hypertension

Another of the twin pregnancy risks is pregnancy-induced hypertension. Multiple pregnancies increase the chances of developing high blood pressure in women. This may at times lead to placental abruption (early detachment of the placenta from its normal position in the uterus). This poses a great risk of the babies dying in the uterus (or intrauterine death), once the placenta detaches itself from the uterine wall. The mother-to-baby connection is disrupted and the baby may not get enough oxygen, nutrients, and other important elements do not flow from mother to baby.

3. Miscarriage

A woman carrying multiple foetuses at once, is more likely to miscarry. The two foetuses are diagnosed in the womb, but one of them suddenly ‘vanishes’ in the first three months, after failing to develop further.

4. Twin-to-twin transfusion syndrome

This is a dangerous twin pregnancy condition that occurs, when two foetuses share a placenta. When blood vessels connect within the placenta, they divert blood from one foetus to another. This situation is known as twin-to-twin transfusion syndrome. This condition eventually leads to one foetus receiving excess blood, that may overload its cardiovascular (heart and blood) system. It may also lead to formation of excess amniotic fluid. In some rare cases, early in a multiple pregnancy, one of the foetuses may die and become flattened, an incidence referred to as foetus papyraceous. The flattened twin is discovered at birth.

5. Caesarean delivery

Multiple pregnancy is more likely to lead to Caesarean delivery in comparison with single deliveries. This is usually due to abnormal foetal position during labour, as well as other obstetric complications.

It is important to note that twin pregnancy risks are not always predictable. Multiple pregnancies may or may not present with any of the known pregnancy complications. What is important, therefore, is close follow-up with your caregiver. It is essential to forestall and treat these complications as they arise.

PG 05 07/28-29