Causes Of Multiple Pregnancy.

How do fertility drugs cause an increase in the rate of multiple births?
Fertility drugs can stimulate the ovaries to release more than one egg, increasing the chance of a multiple pregnancy.

Why are multiple fetuses more common with in vitro fertilization?
With in vitro fertilization, multiple embryos are placed in the uterine cavity in hopes that at least one will implant and grow to maturity.

Do older women really have a greater chance of having multiples?
Yes. The incidence of twins is highest among women between ages 35 and 39. This increase has been attributed to higher levels of gonadotropin, the hormone that stimulates the ovaries to develop and release eggs. As a woman gets older, the level of gonadotropin increases, and she is more likely to produce two (or more] eggs during one menstrual cycle.

I read that the more children a woman has, the more likely she is to have more than one baby. Is this true?
Yes, it is. Research shows that a woman has a greater chance of having twins the more pregnancies she has. We know of one mother who had three single births, then twins, then triplets!

My doctor told me he thinks I may be carrying triplets. How common are they?
Triplets are not common; they occur only once in every 8,000 deliveries. Many doctors never deliver a set of triplets in their entire career!

Is it true that Hispanic women also have a higher incidence of twins and multiple births?
Some studies have shown this is true.

What is the difference between identical and fraternal twins?
Identical (monozygotic) twins develop from a single egg that divides after being fertilized. Babies are always the same sex, and they look alike. When two eggs are fertilized, the babies will be as different in appearance as any other brothers and sisters. They are called fraternal (dizygotic) twins.

Are most twins born to older women fraternal twins?
Usually that is the case. Because babies are born from two different eggs, they are fraternal (not identical).

I've heard that twin births can run in families. Is this true?
Yes, on the mother's side. One study showed that if a woman was a twin, the chance of her giving birth to twins was about 1 in 58! If a woman is the daughter of a twin, she also has a higher chance of having twins. Another study reported that 1 out of 24 twins' mothers (4%) was also a twin, but only 1 out of 60 (1.7%) of the fathers was a twin.

I heard the incidence of multiple births is on the increase. Why is that?
Researchers believe two factors are responsible for this increase.-One is the wider use of fertility drugs or in vitro fertilization, which can result in multiple births. The second is the growing number of women who are having babies at an older age. We know the chance of twins increases as a woman gets older.

A friend told me about her sister-in-law, who was told early in pregnancy she was going to have twins. Then some time later, one of the twins disappeared. Is she making this up?
No, this happens. Early ultrasound exams reveal two babies; later ultrasounds of the same woman show one baby has disappeared, but the other baby is OK. We believe one of the fetuses may die, then be absorbed in the mother's body. This is one reason many doctors prefer not to predict a twin birth before 10 weeks of pregnancy.