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Celebrity Multiple Births
On Thursday, Nick Cannon revealed that he and his wife, Grammy-award-winning singer Mariah Carey, are expecting twins. The couple had been hesitant about revealing too many details about the pregnancy, especially since they suffered a miscarriage in 2008.
While Carey denies using IVF to conceive — she told Us Weekly that she took progesterone and relied on daily acupuncture — multiples are a common effect of fertility treatments, especially in older mothers who usually have more embryos transferred. And Cannon and Carey are not the only celebrities bringing home two bouncing babies. Over the last few years, twins seemed to have become the rage in Hollywood, though talk of fertility treatments and IVF is generally dismissed by the stars.
But how common is it really to give birth to twins, triplets or more?
Dramatic Increases in Number of Multiples
Over the last 30 years, the number of twins has increased sharply. According to the Centers for Disease Control and Prevention (CDC), there were nearly 140,000 twin births in 2007, which is twice the number of twins born in 1980. When looking at triplets or higher order multiples, the birth rate increased 400 percent from 1980 to 1998; however, there has been a slight downward trend since then.
The CDC attributes the increase in multiple births to older maternal age during pregnancy (women in their 30s are more likely to conceive multiples spontaneously) and the growing use and availability of fertility treatments such as ovulation-inducing drugs and in vitro fertilization (IVF).
Conceiving Twins, Triplets and Higher Order Multiples with ART
While some celebrities with twins have remained mum on the use of fertility treatments, research shows that assisted reproduction is the cause of a large percentage of multiple births.
Many celebrities, such as Celine Dion and Marcia Cross, have conceived twins and talked about their use of fertility treatments. In addition, Angela Bassett and Ricky Martin used IVF and surrogacy.
Conceiving multiple pregnancies because of fertility treatments is more common than natural multiple birth conception for several reasons:
- Ovulation-stimulating drugs cause women to release more eggs during a cycle.
- Typically, more embryos are transferred and can implant implanted during IVF, leading to multiple pregnancies.
According to the American Society for Reproductive Medicine report Multiple Pregnancy Associated with Infertility Therapy, 40 percent of triplet and higher multiples was the result of ovulation-inducing drugs without ART, and 40 percent was the result of ART. According to this report, the overwhelming majority of all multiple births arise from spontaneously-conceived twin gestations. However, when looking at pregnancies from assisted reproduction, as shown in the ART Report, more than 30 percent resulted in twins or higher multiples.
Conceiving Multiples Naturally
The sharp increase in the number of multiples born from 1980 to 2007 shows that assisted reproduction and fertility treatments, which became more widely used during this time, have played a big part. However, another reason for the increase in the number of multiple births is that more older women are having children.
A 2006 study in the Netherlands published in the journal Human Reproduction found that older women are more likely to release more than one egg per menstrual cycle and also produce higher levels of FSH, both of which increase the probability of fraternal twins. These patterns were strongest in women aged 35 and older.
According to the ART Report, the likelihood of a multiple pregnancy in the general population is only 3 percent. However, multiple pregnancies of twins or higher multiples make up 30 percent of births from fresh, non-donor IVF cycles.
Celebrities such as Mariah Carey, Jennifer Lopez, Julia Roberts, Geena Davis and Lisa Marie Presley all gave birth to twins while in their late 30s to 40s, but say they did not use fertility treatments or IVF to conceive them.
Complications with Multiple Births
Being pregnant with multiples carries a greater risk to both the fetuses and the mother. The risks to the mother include pre-eclampsia, preterm labor and delivery, gestational diabetes, excess weight gain, and increased gastrointestinal symptoms like constipation. For example, women pregnant with only one fetus have a 15 percent chance of premature labor. Women pregnant with twins, on the other hand, have a 50 percent chance of preterm labor, while women pregnant with triplets have a risk greater than 90 percent.
Risks to the fetus or fetuses include death, fetal growth restriction and prematurity, which can cause cerebral palsy among other health risks and developmental problems. The death of one or more fetuses in a multiple pregnancy conceived through ART is relatively common, especially in the first trimester, and can be observed about 25 percent of the time.
As assisted reproductive technology has advanced, fertility doctors are shifting towards transferring fewer embryos to reduce the risk of multiples. Currently, the ASRM recommends the transfer of only one embryo to women under the age of 35, no more than two embryos for women 35 to 37, no more than three embryos for women 38 to 40, and no more than five embryos for women 41 to 42.