Most multiple gestation pregnancies involve twins.
This article looks at what to do if a doctor diagnoses a multiple gestation pregnancy, the different symptoms that might occur, potential risks, and options for care and delivery.
Having a multiple gestation pregnancy
Multiple gestations do not necessarily create fetuses that will grow to appear identical.
One question that many people ask about a multiple gestation pregnancy is whether the infants will look the same.
In cases of identical twins, the infants will look exactly alike because they come from one fertilized egg that has split into two embryos.
Fraternal twins are not identical and develop when two separate sperm fertilize two different eggs. In cases of fraternal multiples, the fetuses are not genetically identical.
Who will have a multiple pregnancy?
Some women are more likely than others to have a multiple gestation pregnancy.
These women include:
- women who have undergone fertility treatments
- those over the age of 30 years
- those with a family history of multiple gestation pregnancy
- women who have obesity
Are there different types of twin?
To establish which type of twins a woman is carrying, a doctor will need to identify whether each fetus has its own chorion and amniotic sac. To find this out, doctors will carry out an ultrasound exam.
This is a scan that uses sound waves to produce an image of the fetuses.
The amniotic sac is a bag of fluid in the womb in which the fetus grows. Two membranes form the amniotic sac, and one of these is the chorion.
Doctors classify twins into one of three categories:
- Dichorionic-diamniotic: Fraternal or identical twins who usually have their own placenta, chorion, and amniotic sac.
- Monochorionic-diamniotic: Identical twins who share a placenta and chorion but have their own amniotic sac. These twins can experience a complication known as twin-twin transfusion syndrome (TTTS). One twin "donates" blood to the other, resulting in one twin with too much blood and the other with too little.
- Monochorionic-monoamniotic: Identical twins sharing a chorion, amniotic sac, and placenta. These twins experience more frequent complications, including problems with the umbilical cord.
Women who are pregnant with multiples may experience:
- sore breasts
- excessive hunger or rapid weight gain in the first trimester
- simultaneous fetal movements in different areas
- severe morning sickness
- multiple fetal heartbeats
- a larger uterus
- increased levels of substances in the blood known as human chorionic gonadotrophin (hCG) and alpha-fetoprotein
A healthcare provider will confirm the presence of a multiple pregnancy by performing an ultrasound exam.
Some women who are experiencing a multiple gestation pregnancy may require more frequent health checkups, which may include regular ultrasounds.
Other women, especially those who have higher-risk pregnancies, may need to take maternal-fetal medicine.
Diet and exercise are essential for maintaining the health status of the mother and the developing fetuses. While there is no special diet to follow, taking additional folic acid, protein, iron, and calcium can be beneficial.
Taking prenatal vitamins is an effective way to ensure that women get some of the additional nutrients they need. Women who are carrying more than one fetus do not need to take a higher dose than women carrying a single fetus, however.
Always speak to a doctor or midwife before taking any vitamins or other supplements, and take them only as directed.
Exercise is vital for maintaining health during multiple pregnancy.
Discuss exercise options with a healthcare provider, as certain exercises may increase the risk of harming the fetuses.
Yoga, swimming, and walking are generally safe options. Every pregnancy is unique, however, so these exercises may not be suitable for everyone.
Women who are pregnant should partake in an average of 30 minutes of daily exercise.
Sometimes, women experiencing a multiple pregnancy may need to reduce their levels of physical activity.
This may involve:
- reducing exercise and other physical activity later in pregnancy
- getting enough bed rest
- decreasing travel or work activities
A woman carrying more than one infant will gain more weight than a woman carrying a single baby.
According to March of Dimes, women who are carrying twins and who were an average weight before conception might gain anywhere from 37–54 pounds (lbs).
For women who were overweight before conceiving, a safe weight-gain target is 31–50 lbs.
Women who were obese before becoming pregnant should gain a maximum of 25–42 lbs.
Amniocentesis can help identify congenital anomalies.
If a woman requests genetic testing during a multiple gestation pregnancy, it is important to note that some tests using maternal blood may be less sensitive than in single gestation pregnancies.
However, newer blood tests suitable for twin pregnancies are available. In one small study, a specific test to identify Down syndrome showed promising results.
A range of genetic tests, such as chorionic villus sampling (CVS) and amniocentesis, may prove more challenging to complete in multiple pregnancies than in pregnancies involving a single fetus. This is because of the need to test each fetus.
A genetic abnormality might affect one fetus but not the other.
These tests are invasive and can, therefore, pose a risk to the pregnancy.
Risks and complications
According to the American College of Obstetricians and Gynecologists (ACOG), multiple gestation pregnancies often result in higher rates of complication than single gestation pregnancies.
One of the most widespread complications women experience is preterm birth, which is any delivery occurring before 37 weeks.
Some preterm infants may experience health complications, including breathing, eating, and temperature control problems. Some may also experience complications that can lead to cerebral palsy, a group of movement disorders.
Other preterm infants may develop behavioral or learning problems during both childhood and adulthood.
Some infants born at or before 32 weeks of gestation might develop severe health conditions, some of which can be fatal.
Some women carrying multiples might experience the following complications:
- gestational diabetes
- severe morning sickness
- excessive amniotic fluid
- miscarriage and stillbirth
- postpartum depression
- postpartum hemorrhage
As well as TTTS, other possible fetal and newborn complications include:
- spina bifida, cerebral palsy, and congenital heart anomalies
- unequal growth, in which one infant is significantly smaller than the other
- low birth weight, in which an infant is born with a total weight of less than under 5 lbs 8 oz
Women giving birth to more than one infant can either deliver them through the vagina or via cesarean delivery.
The woman expecting a multiple pregnancy and her doctor can decide on the mode of delivery based on several factors.
- the number of fetuses
- position in the uterus
- birth weight and health status
- maternal health
- progression of the labor
- experience of the doctors present
Most often, women with multiple gestation pregnancies will deliver their infants via cesarean delivery.
Pregnancy can raise many questions, especially if a woman is bringing more than one life into the world at once.
Any woman who suspects she may be having a multiple gestation pregnancy should talk to her doctor or midwife.
What is the best way to prepare yourself for multiple gestations?
As with all pregnancies, you can help prepare your body by closely following a nutritious diet, staying active, and discussing with your doctor any health conditions or medications you may be taking. Be sure to abstain from alcohol, tobacco, and recreational drugs.
If you do find yourself expecting multiples, form good support systems with family members, close friends, or even other parents of multiples to help you once the infants arrive.
Also, consider how having more than one infant may affect your work schedule and other obligations, and adjust accordingly.Holly Ernst, PA-C Answers represent the opinions of our medical experts. All content is strictly informational and should not be considered medical advice.