Fertility treatments have been on the rise in recent years – and so has the twin rate. In fact, between 1980 and 2009 the twin birth rate rose by a whopping 76%!
But is IVF the only factor behind the boom in multiple pregnancies? Or are other things at play?
Google ‘how to conceive twins naturally’ and you’ll find loads of suggested foods and supplements.
But the truth? You can’t hack your way to conceiving twins.
It is possible to release two eggs during one cycle naturally. It’s called hyperovulation. But it’s influenced largely by things outside your control.
However, thanks to reproductive science, there are ways to increase your chances of having twins. That said, they do come with some risks.
So, read on to learn how hyperovulation happens and what things boost your chances of releasing more than one egg during ovulation.
What is Hyperovulation?
Halfway through a normal menstrual cycle, one of your ovaries releases an egg. This process is called ovulation.
But sometimes more than one egg may be released in the same cycle. This is known as hyperovulation (or multiple ovulation).
There are two paths to hyperovulation. One ovary may drop more than one egg or both of your ovaries may release an egg in the same cycle.
Let’s dig into the science behind this phenomenon.
The Science Behind Multiple Ovulation
Many hormones play a role in hyperovulation. But the leading role goes to FSH.
Aptly named, follicle-stimulating hormone (FSH) stimulates the growth of ovarian follicles. Follicles are fluid-filled sacs that house an immature egg.
At the beginning of your cycle (aka ‘the follicular phase’), your body starts producing more FSH. This causes several eggs to start maturing within their follicles.
But midway through the follicular phase, FSH begins to dip. Typically, only the strongest, healthiest follicle is able to survive the drop in FSH. This is known as the ‘dominant follicle.’
Once the dominant follicle emerges, the extra follicles die off. The dominant follicle then begins producing estrogen.
As estrogen levels rise, it causes luteinizing hormone (LH) to surge. This surge triggers ovulation, causing the ovary to release the egg.
While releasing one egg per cycle is the norm, it’s possible to release two or more eggs.
How Common is Hyperovulation?
One 2003 study performed ultrasounds on 50 healthy women in their reproductive years. They tracked their follicle development – and the results were surprising.
Nearly two-thirds of the women experienced two waves of follicle development. What’s more, 32% of them had three waves!
Now keep in mind – follicle development does not equal ovulation.
It shows it’s possible to release two… or even three eggs during ovulation.
Another 2006 study used ultrasounds on 507 women over one to three cycles. They found that nearly 21% of women had multiple ovulations for at least one cycle.
They also learned that women who hyper ovulated had much higher levels of FSH than those who released one egg.
This may explain why women with elevated FSH levels are more likely to have twins.
What Factors Increase the Odds of Hyperovulation?
Several things can influence your chances of having a multiple pregnancy. Here are a few:
Identical twins may happen by sheer luck, but genetics play a major role in fraternal twins.
Scientists have discovered certain genes that may increase the chances of having fraternal twins. These genes are linked with higher FSH levels, which makes twins more likely.
That said, when it comes to twins, only the mother’s genes matter, as they’re the ones that affect ovulation. For example, if your mother or sister had twins, you’re twice as likely to have them yourself.
As your age increases, so does your chance of conceiving twins. One study found that being over 35 doubles the likelihood of twins. Here’s why…
Women are born with a finite number of eggs. The older you are, the fewer eggs you’ll have. As this pool of eggs shrinks, the body requires more FSH to stimulate follicle growth. This FSH boost may cause some women to release more than one egg.
Hyperovulation is more common among certain ethnicities. Women in African countries are most likely to conceive twins, with around 23 out of 1,000 births resulting in twins. Twinning is least common for Asians, happening in roughly 5-6 out of 1,000 births.
Research shows that women who are taller (over 164 cm or roughly 5’4) are 1.5 to 2.0 times more likely to have twins than shorter women. Experts suspect insulin growth factor (IGF) may be the culprit.
IGF is a hormone released from the liver that enhances sensitivity to FSH. Since taller women tend to have higher IGF levels, this may explain the height advantage.
A 2008 study from Fertility and Sterility found that having a higher body mass index (BMI) increases the chance of having twins. In the study, overweight and obese women were more likely to have twins than women with a normal BMI.
That said, being overweight and obese poses many health risks. So, you shouldn’t gain weight just to up your chances of twins.
Women who are breastfeeding while conceiving are more likely to have twins. One study found that the twin rate for breastfeeding women was ten times higher than for women who weren’t breastfeeding.
Stopping birth control
According to one 1977 study from the New England Journal of Medicine, some women who go off birth control may release more than one egg.
In the study, the twin rate doubled for women who’d recently gone off oral contraception. It’s believed that as your body readjusts to ovulation, it may overshoot the mark, causing multiple ovulation.
Twins & Triplets: How Do Multiple Pregnancies Happen?
There are a few paths to multiple pregnancies. One occurs at random, while the other depends on hyperovulation.
Identical twins, or monozygotic twins, occur randomly when a fertilized egg splits into two. This usually happens within 10 days after conception.
Because they share the exact same genes, identical twins always look the same and are the same sex.
Fraternal twins, also known as dizygotic twins, are the result of hyperovulation. They occur when two eggs are released and fertilized in the same cycle.
Unlike identical twins, fraternal twins don’t share the same genes. That’s why they’re often different sexes and don’t look the same.
How to Release Two Eggs ?
Many of the twin factors above, such as age and genetics, are out of your control. However, there are reproductive treatments proven to increase hyperovulation.
Some fertility medications, such as clomiphene citrate, encourage the body to release extra eggs. Sometimes gonadotropin medications are prescribed as well. These drugs spur multiple eggs to grow in the same cycle.
Women taking these drugs need to be closely monitored. If too many eggs mature at the same time, you run the risk of becoming the next ‘octomom.’
Also, some fertility meds (e.g. gonadotropins) may increase the risk of ectopic pregnancy. This is when the fertilized egg implants outside the uterus, usually in the fallopian tube.
Disclaimer – Fertility medications can be a helpful tool if you’re struggling to conceive. But you should always consult with your doctor for a diagnosis beforehand. That way, they can find the right fit for you.
Intrauterine insemination (IUI)
Also known as ‘artificial insemination’, IUI involves inserting sperm into the uterus. Fertility drugs are often used with IUI, which increases the chances of releasing more than one egg.
IUI is a fairly low-risk procedure. Although sometimes infections or spotting may occur. The greatest risks for IUI come from the fertility drugs taken before the procedure.
In vitro fertilization (IVF), one of the most common fertility treatments, involves many steps.
First, fertility drugs are used to stimulate hyperovulation. Eggs are then collected and fertilized by sperm in a lab. The embryo (or embryos) are then implanted into the woman’s uterus.
Women who undergo IVF treatments are much more likely to have a multiple pregnancy. In fact, around 20-30% of successful IVF cycles result in twins.
IVF can also increase the risk of developing ovarian hyperstimulation syndrome (OHSS). This causes the ovaries to swell and leak fluid into the body.
Common Myths About Hyperovulation
The internet is swarming with myths about how to increase your chances of having a multiple pregnancy. So, let’s bust some of them…
Myth #1: Certain foods increase fertility for twins
One 2006 study found that women who consume dairy are five times more likely to have twins than vegan women.
Why? Some suspect it’s because many dairy products are high in growth hormones that may boost IGF. Since IGF enhances sensitivity to FSH, this may up the chances of releasing more than one egg.
Yams are another ‘twinning food’ that gets a lot of attention. This is because the Yoruba tribe in Nigeria has the highest twinning rate on earth, with 45 out of 1,000 pregnancies being twins.
Many pin the Yoruba twin rate on their diet, which is rich in yams. Some believe that because yams are high in phytoestrogens, they may influence fertility.
Yet, other nearby villages eat the same diet, without the mega-high twin rate. So while eating yams won’t hurt, there’s no evidence they’re the secret to twins.
Myth #2: Folic acid can cause hyperovulation
Some say folic acid may play a role in the twin boom. This is because as folic acid supplementation amped up, so did the twin rate.
For now, there’s no evidence that folic acid helps you get pregnant with twins. But it does prevent neural tube defects. These are birth defects that affect the brain, spine, and spinal cord. So, whether you want twins or not, folic acid is a must for a healthy pregnancy.
Myth #3: Exercise will increase your chances of twins
Nope. There’s no evidence that working up a sweat boosts hyperovulation. That said, moderate physical activity such as brisk walking does improve fertility. Just don’t go overboard, as vigorous exercise can actually harm fertility.
Risks Involved in Multiple Pregnancies
While twins and triplets can be an exciting way to grow your family, multiple pregnancies do come with some risks.
Preterm birth: Roughly 60% of twins and 90% of triplets are born prematurely (before 37 weeks).
Low birth weight: Multiples born prematurely are at increased risk of low birth weight (under 5.5 pounds).
Cesarean section: Delivery is more complicated with twins and triplets, So, C-sections are more likely.
Preeclampsia: This condition happens 2 to 5 times more often in mothers carrying multiples. It causes high blood pressure during pregnancy.
Gestational diabetes: Research shows having multiple increases the risk of gestational diabetes. It’s believed that when multiple placentas produce hormones, it affects insulin sensitivity.
Summing it Up
- Hyperovulation or multiple ovulation is when your body releases more than one egg during the same cycle.
- Scientists have linked higher FSH levels with hyperovulation.
- Identical twins occur when a fertilized egg splits into two. Fraternal twins are the result of hyperovulation.
- Genetics, age, height, weight, and ethnicity all play a role in whether you release more than one egg during ovulation.
- Fertility treatments such as IVF and fertility meds can increase the chances of hyperovulation. But they do come with risks.
- Multiple pregnancies do come with risks. This includes preterm birth, low birth weight, cesarean delivery, gestational diabetes, and preeclampsia.