Twin pregnancies are becoming more common with increasing use of fertility treatments. Yet, when your healthcare provider confirms "you have TWINS!" there is usually an element of surprise and questions. Your first question may be, what does this mean for my pregnancy?
Three things that will have implications on the management of your pregnancy are:
How many eggs were fertilized, the genetic nature of your pregnancy. Twins can be monozygotic, with genes from one egg and one sperm cell or dizygotic, with genes from two eggs and two sperm cells. Monozygotic twins are identical twins. Dizygotic twins are fraternal twins.
How many placentas developed? The number of chorionic membranes around each baby will indicate the number of placentas that are developing. The chorionic membrane is around the amnion. Monochoronic, one membrane, indicates that the babies share one placenta. This presents a higher risk pregnancy that will require closer medical management. Dichorionic, two membranes, occurs with fraternal twins or identical twins when the fertilized egg divides within the first 3 days after conception.
How many amniotic sacs developed? This is determined by number of amniotic membranes around the amniotic sac and babies. Monoamniotic, one membrane, indicates that the babies share one amniotic sac. This presents the possibility of umbilical cord entanglements requiring frequent monitoring later in your pregnancy and usually a Cesarean birth. Diamniotic, two membranes, indicates that each baby has their own amniotic sac.
The number of placentas and amniotic sacs are usually determined by ultrasound at 11 to 14 weeks gestation. The number of fertilized eggs may be disclosed by identifying a boy and a girl proving fraternal twins or sharing one placenta proving identical twins. Sometimes the number of fertilized eggs is not known until a genetic test can be done after birth.
Prenatal Care
Your twin pregnancy increases your risk factors for preterm birth, gestational diabetes, and development of high blood pressure. If your twins share one placenta they will be at risk for the complication of twin-to-twin transfusion. You can expect more frequent checkups with your health care provider to monitor your health and your babies’ growth and development.
Preterm labor symptoms like cramping, intermittent low back pain or vaginal discharge changes such as bleeding or leaking fluid need to be evaluated by your health care provider. Call your health care provider when you notice any of these changes.
Gestational diabetes develops from the increased insulin resistance of pregnancy. A nutritional diet avoiding sugary drinks and limiting sweets can help you maintain appropriate weight gain and avoid gestational diabetes. A diabetes educator can help you to learn how to monitor and manage your blood sugar levels during your pregnancy.
Gestational hypertension or pre-eclampsia, a more serious disorder, can develop during any pregnancy. Your twin pregnancy increases your risk of hypertensive disorders. The causes of gestational hypertension or pre-eclampsia are not clear. Your health care provider will monitor your blood pressure and lab work to identify and treat this condition early. If serious pre-eclampsia develops your health care provider may recommend early delivery to protect your health.
Twin-to-twin transfusion may occur when identical twins share one placenta. One baby receives too much blood supply, and the other baby receives too little. This serious complication will require specialized care. In complicated cases a minimally invasive surgery may help both babies thrive.
Labor and Delivery Care
Many twins are delivered vaginally. If the first twin is in a head down, vertex, position you may labor as usual and be moved to the operating room for delivery. If your second twin moves into a favorable position for delivery, then your delivery will be completely vaginal. You will be in the operating room to protect your second twin. If a cesarean delivery becomes necessary, it can be done in a timely manner.
If your first twin is not in a head down position or if complications occur that make laboring too dangerous for you or your babies, a cesarean delivery becomes necessary.
Understanding your twin pregnancy is a first step towards holding your beautiful babies!
Pregnancy week by week, Twin pregnancy: What twins or multiples mean for mom, Sandhya Pruthi, M.D, Nov 4, 2022.
Zygosity, The Role of Cell-Free DNA-Based Prenatal Testing in Twin Pregnancy
Fiona L. Mackie, Mark D. Kilby, in Noninvasive Prenatal Testing (NIPT), 2018
What are the symptoms of preterm labor? NICHD-Eunice Kennedy Shriver National Institute of Child Health and Human Development
Twin-to-Twin Transfusion Syndrome, Yale Medicine
Manual of Obstetrics, 8th edition, Arthur T Evans MD, Emily DeFranco, DO, MS, 2014, pp 634-644. Assessed and Endorsed by the MedReport Medical Review Board