Fertility drugs enhance the chances of conceiving by stimulating the ovaries to produce more eggs. However, more than one egg can be fertilized increasing the probability of multiple pregnancy.
Twin pregnancy occurs in approximately 8% of patients using clomiphene citrate while the risk of triplet pregnancy is less than 1%. The risk of twin pregnancy with injectable gonadotropins plus insemination is approximately 20% while the risk of triplets can be between 1% and 3%.
In IVF the risk of multiple pregnancies depends on the number of embryos transferred back to the uterus. Patient and doctor can discuss the risk of multiples and decide on the number of embryos that is appropriate considering both patient’s choice and medical indications.
Multiple pregnancies are associated with significant higher risks than singleton pregnancies, including pregnancy-induced high blood pressure, pregnancy diabetes, maternal bleeding, premature labor, premature delivery, low birth weight babies, and Caesarean delivery (C-section). Low birth weight and preterm babies have an increased risk of respiratory, neurological and other long term complications.
Fertility treatments, are associated with a risk of ectopic pregnancy (a pregnancy which occurs outside the womb, usually in the fallopian tube). Ectopic pregnancy can occur both with natural conception and with infertility treatment. The incidence of ectopic pregnancy after IVF and embryo transfer is about 1.5%-2.5%. Generally, surgical treatment is required, but in the early stages it may be possible to use a drug to treat the ectopic pregnancy.
This is a rare twin pregnancy characterized by one twin positioned correctly in the womb and the other in an abnormal place such as the fallopian tube. The incidence of this uncommon condition increases after IVF or others related treatments.
The risk of miscarriage after IVF is comparable to the risk commonly quoted for the general population. However there is variability in the numbers reported by different studies. According to recent Canadian statistics the risk of miscarriage following IVF is about 16%. In general, assisted reproduction does not prevent or increase the risk of miscarriage.