Yes, most twin pregnancies have positive outcomes with healthy babies, but they are considered higher-risk and more prone to complications like premature birth, low birth weight, and conditions such as preeclampsia and gestational diabetes, requiring closer monitoring despite high survival rates. While the risk of issues like stillbirth and neonatal death is higher than single pregnancies, excellent modern care significantly improves success, with the vast majority of twin infants surviving and thriving, often needing only brief NICU stays.
In the U.S., fewer than 3% of pregnant women have twins. Worldwide, twins make up only 2% to 4% of births. Fraternal twins (where two eggs are fertilized by different sperm in the same cycle) are about twice as common as identical twins (when one fertilized egg splits into two embryos).
Increased risk of miscarriage
A woman is at increased risk of miscarriage if she has twins or carries multiples. Various studies have shown that women with twins are more likely to miscarry than those with singleton pregnancies, however, all studies have shown that the risk is still between 5-13%.
A little more than half of twin pregnancies end in preterm delivery (before 37 weeks). While 40 weeks is the full gestation period of the average pregnancy, most twin pregnancies are delivered at approximately 36 weeks (range 32-38 weeks depending on the type of twin pregnancy).
The chances of twins increase significantly after the age of 35, with women over 40 being more likely to conceive twins compared to younger women. This increase is largely due to a rise in the production of follicle-stimulating hormone (FSH).
Age: If you're over the age of 35, you're more likely to release multiple eggs during ovulation. Family history: If your mother's side has a history of fraternal twins, there is a chance you could conceive twins naturally.
However, males are also more susceptible than females to die in utero, and since the death rate in utero is higher for twins, it leads to female twins being more common than male twins.
Sadly, pregnancy loss in the first 12 weeks is common. The risk of losing a baby in the first two trimesters of a twin pregnancy is slightly higher than with a single pregnancy.
Twin development at 24 weeks
At 24 weeks, they are considered viable and could possibly survive outside of the womb - in an intensive care unit, with a lot of help.
Potential health complications in a twin pregnancy
Women with twin pregnancies are more likely to have pregnancy health problems and complications like gestational diabetes, pre-eclampsia, premature labour and bleeding. Twins who share a placenta might have extra complications.
Premature birth
Twins and triplets have a higher risk of being born prematurely (before 37 weeks) and having a low birthweight. Your risk is also increased if you've given birth prematurely before, or if a cervical length scan found that you have a short cervix. Most twins and triplets are born prematurely.
Your risk of miscarriage is greatest between weeks 0 and 10. In the early days of pregnancy, you likely don't yet know you're pregnant.
How to Protect Your Health and Wellness During Twin Pregnancy
The gene for hyperovulation can come from either side of the family, but the woman would need to have the gene in order for the couple to have twins based on genetics. In other words, twins on the father's side of the family will have no influence on your chances of having twins.
Early loss (miscarriage) of a twin or multiple
These early losses, often called vanishing twin syndrome, are fairly common, affecting between 10 and 40 percent of multiple pregnancies.
What causes you to get pregnant with multiples? A multiple pregnancy means you're pregnant with more than one baby. Multiple pregnancy usually happens when more than one egg is fertilized. It also can happen when one egg is fertilized and then splits into 2 or more embryos that grow into 2 or more babies.
Full-term for twins is the same as full-term for singleton babies, technically: 39 weeks pregnant. But if your twins are born at 37 weeks, that's as close to actual full-term as many twins get. At that point, they have full lung maturity and should be able to leave the hospital within a few days of delivery.
First Trimester:
An early ultrasound (around six to nine weeks) can show if you're having twins and whether they're identical or fraternal. This scan also helps determine if your babies share a placenta or sac, which affects your care plan.
Monochorionic-diamniotic twins are identical twins that share a placenta but each develops in their own separate amniotic sac. This is the most common type. Monochorionic-monoamniotic twins are identical twins that share both a placenta and an amniotic sac. This is the rarest and highest risk form of twin pregnancies.
Vanishing Twin Syndrome is more common than many realise. With the increased use of early ultrasound, it's estimated that the condition occurs in up to 30% of twin pregnancies. Many cases go undetected because the loss happens before the first prenatal ultrasound.
"One of the things that is postulated as causing morning sickness is high levels of human chorionic gonadotropin, and we know that levels of this hormone are higher in twin pregnancies, so women carrying twins have a higher incidence of nausea and vomiting in the first trimester," says Al-Khan.
Dichorionic/Diamniotic (Di/Di) Twins
Each baby has their own placenta and their own amniotic sac. This is the most common and typically the lowest-risk type of twin pregnancy.
As you get older, the likelihood of conceiving twins increases. The higher rate of twin pregnancy with age is linked to hormones. Researchers have found that as women get older, they produce more follicle-stimulating hormone (FSH). FSH is what encourages the ovaries to produce eggs.
Fraternal twins come from two separate eggs, so they can be any combination: girl/girl, boy/boy, or boy/girl. Different-sex identical twins are extremely rare. This can happen through unusual genetic changes or in ultra-rare “semi-identical” twins – but there are only a handful of documented cases worldwide.
The Early Signs of a Twin Pregnancy