It is estimated that there is a 40% chance of giving birth to twins if you become pregnant with assisted reproductive technologies. The incidence of twins in the general population is approximately 1-2% of pregnancies. This increased risk is largely due to the higher number of embryos implanted when using In Vitro Fertilization (IVF) in most Canadian provinces.
In addition to IVF, many drugs and hormone treatments used during fertility treatments increase the risk of multiple births. Clomiphene citrate, a common drug used to stimulate ovulation, causes a small increase to the risk of conceiving twins.
So why is a multiple birth considered a risk? Many parents of twins are happy with that outcome. However, with multiple births, there is a drastically increased risk of premature birth and low birth weight. There is also an increased risk of miscarriage with multiples.
Babies born prematurely face many risks, including:
- Underdeveloped lungs, which will require the baby to breathe with the assistance of a ventilator. Babies born with underdeveloped lungs may have to remain in the hospital for months after birth.
- Heart problems caused when the large artery that allows blood to bypass the lungs while baby is in the womb fails to close after birth. These problems can usually be fixed with drugs and surgery.
- Birth injuries due to the increased fragility of undersized babies. Birth injuries such as bruises, broken bones, Erb’s palsy and cerebral palsy may all be more common in cases of multiple births.
- Bleeding in the brain can occur due to more fragile blood vessels. These bleeds will often resolve themselves but can sometimes lead to long-term neurological problems.
- Cerebral palsy is one of the most common problems that affect multiples. It is a neurological problem that affects movement and balance. Cerebral palsy is often caused during birth when the baby’s brain is injured or the baby suffers from a lack of oxygen. Premature babies, being smaller and more fragile, seem to be at greater risk.
Multiple births pose an increased risk to the mother’s health as well. Mothers carrying multiple babies may have to spend several weeks on bed rest in order to delay the onset of labour. There is also a higher chance of having to deliver multiples by cesarean section. Mothers carrying multiples may also be at higher risk of developing anemia, pre-eclampsia or gestational diabetes.
In order to minimize the risks of fertility treatment, discuss with your doctor the possibility of implanting only one embryo during IVF. Unfortunately, for many Canadians the cost of IVF treatments makes it impractical to implant only one embryo at a time.