Conception
Conception happens when the sperm fertilizes an egg within days of ovulation.
Menstrual cycles average 28 days and ovulation typically happens mid-cycle—around day 14. A woman’s ovary normally releases one egg during ovulation. There are two ways twin pregnancies can occur:
Fraternal twins: When one or both ovaries release more than one egg during ovulation and each egg is fertilized and implants in the uterus. Identical twins: When a single fertilized egg splits into two identical embryos.
Identical twins are rarer than fraternal twins.
The first definitive symptom of any pregnancy is missing a period. While it may take awhile before you know you are carrying twins, there are some indicators.
Are older than 35 years oldHave a family history of twinsHave a partner with a twinHave conceived through in vitro fertilization (IVF)
Symptoms
Women pregnant with twins have the normal symptoms of a single pregnancy, but oftentimes they are more pronounced.
For example, if you’re pregnant with twins, your human chorionic gonadotropin (hCG) levels will rise faster and higher than in a single pregnancy. More of this hormone makes nausea more severe. Fatigue and breast tenderness are other symptoms in the first trimester that may be worse than if you were pregnant with a single fetus.
Additionally, you will gain more weight, which puts more strain on your body as your pregnancy progresses, and can cause more exaggerated symptoms such as swelling and body aches.
It is important to keep your weight as close to these guidelines as possible through healthy eating and exercise to lessen the additional risks associated with having twins.
37 to 54 pounds for normal-weight women31 to 50 pounds for overweight women25 to 42 pounds for obese women
First Healthcare Provider’s Visit
Prenatal care is critical during pregnancy. If you conceive naturally, your first OB visit usually happens toward the end of your first trimester. If you conceive through IVF, you may see your healthcare provider sooner. Either way, the first major checkup usually happens toward the end of the first trimester (about nine to 12 weeks), even if you have seen your healthcare provider sooner than this. This visit may be when you learn that you are having twins.
During this appointment, your healthcare provider will review your health history, perform physical and pelvic exams, and give an overview for treatment during your pregnancy. Preparing a list of questions to ask your healthcare provider will help you remember them.
Most women will also get the first ultrasound of their fetuses to check their heartbeats and anatomy. Your healthcare provider will run other tests to check for genetic abnormalities in the babies through bloodwork. Sometimes you may be offered a blood test that will reveal the gender of the fetuses. Your healthcare provider will calculate how many weeks pregnant you are and set a due date for the babies.
After the first visit, the standard schedule to see your OB-GYN is:
Every four weeks until 28 weeksEvery two to three weeks from 28 to 36 weeksWeekly from 36 weeks until delivery
You may need to see your OB-GYN more frequently than the standard schedule.
Risks and Complications
Carrying two babies is more taxing on your body than a single pregnancy. A number of risks are associated with twin pregnancies, and a number of complications may occur. The following are the most prevalent.
Preterm Labor and Birth
Preterm labor and birth are the most common complications in twin pregnancies. Preterm is defined as delivering a baby before 37 weeks gestation. Twin pregnancies average 36 weeks long.
Both being pregnant with twins and using assisted reproductive technology are associated with a higher risk of preterm labor and birth. One study showed that more than 50% of twin births occurred preterm, compared with only 10% of births of single babies.
Complications of preterm delivery depend on how early the babies are delivered. The earlier they are born, the higher the risk for complications. These can include:
Immature lungs Respiratory distress syndrome Apnea and bradycardia Infection Jaundice Pneumonia Inability to maintain body heat
Intrauterine Growth Restriction
Intrauterine growth restriction (IUGR) or small for gestational age (SGA) is a condition that happens when one or more of your babies isn’t growing at the proper pace. This condition might cause the babies to be delivered prematurely or at a low birth weight. Nearly half of pregnancies with more than one baby have this problem.
Your healthcare provider will monitor your pregnancy for IUGR, usually by ultrasound, to ensure your babies’ development is on track. Babies born with IUGR are at an increased risk for:
Birth by C-section Hypoxia (lack of oxygen when a baby is born) Meconium aspiration, which is when a baby swallows part of the first bowel movement Hypoglycemia (low blood sugar) Polycythemia (increased number of red blood cells) Hyperviscosity (decreased blood flow due to an increased number of red blood cells) Motor and neurological disabilities
Your healthcare provider may manage IUGR with:
Frequent monitoring with ultrasoundsTracking fetal movementsCorticosteroid drugsHospitalizationEarly delivery and sometimes an emergency C-section
When to deliver for a woman with IUGR will often depend on:
Gestational ageFetal well-beingThe amount of amniotic fluid
Preeclampsia
Preeclampsia is when a woman develops high blood pressure and a protein in her urine during pregnancy. There is a greater chance of preeclampsia with twin pregnancies. It also may occur earlier and be more severe in pregnancies with multiples.
Preeclampsia can damage many organs in your body, most commonly:
KidneysLiverBrainEyes
Preeclampsia can also:
Put a baby’s health at riskCause placental abruptionCause low birth weightCause preterm birth
Because of the risks involved for mom and babies, when preeclampsia occurs during pregnancy, the babies may need to be delivered early even if they are not not full term.
Signs of preeclampsia include:
Headaches Blurry vision Dark spots appearing in your vision Right side abdominal pain Rapid swelling in the hands and face (edema) Rapid weight gain
You can lower your risk of preeclampsia by maintaining a healthy weight, exercising, and following a healthy diet before pregnancy. All of these steps are even more important during pregnancy per your healthcare provider’s orders.
Still, some women develop preeclampsia despite taking preventive measures. Women with preeclampsia, especially those carrying twins, require close monitoring by their healthcare provider because of potentially serious complications.
Low Birth Weight
Low birth weight is another common complication with twin pregnancies since many twin pregnancies are preterm deliveries. Low birth weight is defined as a baby weighing less than 5 pounds 8 ounces at birth.
Babies weighing less than 1,500 grams (3 pounds, 5 ounces) at birth are considered very low birth weight. Babies weighing less than 1,000 grams (2 pounds, 3 ounces) at birth are considered extremely low birth weight.
The two main causes of low birth weight are:
Prematurity: Babies born prematurely (before 37 weeks) primarily account for low birth weight babies. Significant weight gain occurs in the last weeks of pregnancy, so by delivering early, a baby misses the final growth stages. Intrauterine growth restriction: Discussed above, this is another condition that accounts for low birth weight, but in a full-term baby.
Complications for low birth weight babies include:
Low oxygen levels at birthTrouble staying warmTrouble feeding and gaining weightInfectionBreathing problems and immature lungs (infant respiratory distress syndrome)Nervous system problems, such as bleeding inside the brainDigestive problemsSudden infant death syndrome (SIDS)
Nearly all low birth weight babies require time in the neonatal intensive care unit (NICU) until they weigh enough and are well enough to go home.
Gestational Diabetes
Gestational diabetes—which is high blood glucose (sugar) levels during pregnancy—impacts twin pregnancies more often than single pregnancies.
Pregnant women are routinely tested between 24 and 28 weeks for gestational diabetes because of the risks this condition poses. You may be screened earlier if you are at a higher risk for gestational diabetes. Risk factors include:
Being overweight or obese Having gestational diabetes in a previous pregnancy Having high blood pressure Having a history of heart disease Having polycystic ovary syndrome (PCOS)
Uncontrolled blood sugar can cause complications during pregnancy for mothers and babies including:
Large babies: Uncontrolled blood sugar in a mother drives up babies’ blood sugar, too. This can lead to babies growing too big. C-section: Women whose blood sugar isn’t well controlled have a higher risk of delivery by cesarean. Preeclampsia: Preeclampsia is already more common in twin pregnancies. Women with diabetes have high blood pressure more often than women without diabetes. Hypoglycemia (low blood sugar): This is a potentially life-threatening side effect from taking medications to control blood sugar.
In many cases, gestational diabetes can be managed through exercise and a healthy diet. However, some women will also require treatment with insulin.
Placental Abruption
The placenta attaches the fetuses to the mother’s uterus. It is a life source that gives food and oxygen to the fetuses through the umbilical cord. Placental abruption happens when the placenta separates from the uterus before birth. In most cases, the placenta stays attached to the uterus.
When placental abruption occurs, the uterus and all it provides is compromised. Placental abruption is an emergency and requires immediate care because it is life-threatening to the babies and potentially the mother. It can lead to:
Premature birth and low birth weightHemorrhaging in the motherDeath to a baby (in rare cases)
About 1 out of 100 pregnancies has placental abruption. This condition usually happens in the third trimester, but it can also happen after 20 weeks of pregnancy.
The most common symptom is vaginal bleeding with pain during the third trimester of pregnancy. Sometimes the blood will be behind the placenta. In that case, there will be no bleeding. Symptoms also can include:
Abdominal painUterine contractionsTender uterusBackache
If you have these symptoms, it’s critical that you get evaluated by a healthcare provider.
Twin-to-Twin Transfusion Syndrome
In twin-to-twin transfusion syndrome (TTTS), identical twins (or other multiples) share a placenta. Within the placenta, they share a network of blood vessels that supply nutrients and oxygen essential to survive and develop in utero.
When TTTS occurs, there is an unequal sharing of blood that passes between twins through blood vessel connections in the placenta. One twin (the donor twin) pumps blood to the other twin (the recipient twin). This causes the donor twin to receive too little blood and the recipient twin to receive too much.
This unequal distribution of blood and nutrients can lead to severe complications and even death in one or both twins. When the donor twin gives away more blood than it receives in return, the fetus runs the risk of:
MalnourishmentNo amniotic fluid surrounding itA small or absent bladderOrgan failure
The recipient twin receives too much blood and is at risk for cardiac complications, including hydrops.
A critical factor in determining the prognosis of TTTS is the level of cardiovascular dysfunction in the fetuses. For this reason, TTTS diagnosis includes a detailed examination of the fetal heart by using fetal echocardiography in both the recipient and donor twin.
TTTS is confirmed by ultrasound and other specialized tests that measure amniotic fluid, blood flow, and bladder filling in the detail.
Healthcare providers use the Quintero staging system to determine the severity of TTTS.
Treatment options include:
Amniocentesis, to drain off excess fluid. This appears to improve the blood flow in the placenta and lower the risk of preterm labor. Amniocentesis can save approximately 60% of affected babies. Laser surgery can also be used to seal off the connection between the blood vessels and appears to save 60% of affected babies. Delivery is also an option if your babies have developed enough to survive outside the womb.
C-Section
Cesarean (C-section) deliveries entail a surgical cut across the lower abdomen to remove a baby from the uterus. They are done when a vaginal delivery is not safe for a baby or mother, or when there’s a need for an emergency delivery.
C-sections are more common in twin pregnancies than single deliveries. This is because the conditions that raise the risk of C-section (low birth weight, gestational diabetes, preeclampsia, placental abruption, and IUGR) occur more often in women pregnant with twins.
However, twins are frequently delivered vaginally depending on factors relating to the presentation and gestation of the babies. Vaginal deliveries with twins are possible when:
The gestation is greater than 32 weeksTwin A (the baby closest to the cervix) is the largestTwin A is head downTwin B is head down, breech, or sidewaysTwin B is smaller than twin AThere is no evidence of fetal distress
C-sections are sometimes planned and sometimes not when there are emergency situations. There are some inherent risks associated with the surgery:
InfectionBlood lossA blood clot that leads to embolismInjury to the bowel or bladderAn incision that might weaken the uterine wallAbnormalities of the placenta in subsequent pregnanciesRisks from general anesthesiaFetal injuryThe possibility you can’t have vaginal births in future pregnancies
A Word From Verywell
Pregnancy can be one of the most rewarding periods of a woman’s life. If you are pregnant with twins, it is important to maintain a close relationship with your healthcare provider to ensure the best outcomes for you and your babies.
