How does a twin pregnancy happen?
You can be pregnant with either identical (or monozygous) twins or fraternal twins.
Conceiving identical twins starts with a single sperm fertilizing an egg. This fertilized egg then divides into two, which results in identical twins. The babies born are of the same sex, and they share the same DNA. But the chances of conceiving identical twins are very slim.
Fraternal twins are not identical. They're conceived when two separate eggs — released by the ovaries — are fertilized by two sperm cells. Unlike identical twins, fraternal twins don't have the same DNA. They don't look alike and can be of different sexes. Fraternal twins occur more than identical twins, but they don't occur at will. The ovaries rarely release more than one egg.
Natural ways to increase your chances of having a twin pregnancy
Here are some steps you can take to increase your likelihood of having your ovaries release more than one egg at a time.
Getting pregnant in your 30s or later
You are more likely to conceive twins when you are over 30. This likelihood spans from increased production of the follicle-stimulating hormone — or FSH. This hormone is responsible for egg development in the ovaries.
Higher levels of FSH are required as people get older because more stimulation is required for egg growth. The increased FSH levels resulting from lower fertility sometimes causes the follicles to overreact. This causes the release of multiple eggs that bring about multiple births.
Finding a partner with a family history of twins
It is more likely that children of male identical twins reproduce identical twins. Having fraternal twins in your family increases your chances of having twins too. When there are fraternal twins on both the father and mother's side, the chances of having twins might increase further.
Increasing your weight
People who are obese — with a body mass index of over 30 — have increased chances of twin pregnancies. The levels of estrogen — a female sex hormone — increase with extra body fat. The weight increase leads to excessive stimulation of the ovaries. The ovaries might release multiple eggs instead of one. But there are other factors that can make conceiving difficult for people with obesity.
Conception during breastfeeding can increase the chances of twin pregnancies. Breastfeeding can reduce fertility during the first six months of delivery, where a mother breastfeeds her baby exclusively. However, it is possible to become pregnant with twins while breastfeeding. A study found that the rate of twin pregnancies in women not breastfeeding was 1.1 percent — which was much lower than that in breastfeeding women (11.4 percent).
Consuming dairy products
Consuming a lot of dairy products increases the chances of a twin pregnancy because the growth hormones released by cows into their milk cause changes to your hormonal levels.
Getting pregnant repeatedly
It isn't clear why but having one or several previous pregnancies increases your chances of having twins. It's speculated that this probably happens because by the time you have your second or later pregnancy, you become older — possibly over 30.
Using fertility treatment
The IUI procedure itself doesn't increase your twin pregnancy chances but the medications taken along with the procedure. Clomiphene (Clomid) and letrozole (Femara) are fertility medications that stimulate ovulation. These medications are given during IUI cycles. They may cause your body to produce multiple eggs — leading to multiple eggs being fertilized, resulting in twin pregnancies.
Gonadotropins (Chorex) — which stimulate egg follicle growth and are usually injected during IUI and some other fertility treatments — also increase the chances of multiple births.
Mothers receive medications during the IVF procedure. In this procedure, the main thing responsible for increasing the chances of twin pregnancies is the number of embryos you choose to transfer. You might decide to transfer one embryo, hope it splits into two, and lead to pregnancy with twins.
If you transfer multiple embryos, there's an increased possibility of fraternal twins occurring. The two or more embryos could successfully attach and develop into a set of twins or more.
Though there isn’t any special drug that guarantees twin pregnancy, you can increase your chances of becoming pregnant with twins. Following any of these suggestions will increase your chances of a twin pregnancy, but remember that twin pregnancy has its risks and rewards. It's not all fun and cuteness.
Twin pregnancy is more susceptible to perinatal morbidity and mortality. Also, there can be maternal complications like preterm labor. That doesn’t mean you can't have a healthy twin pregnancy. You would only need more care and attention.