Guide to Pregnancy
Prenatal Care Guide
How common are twins?
|What Types Of Twins Are There?
Fraternal twins: Two thirds of all twins are fraternal. It means 2 separate eggs are fertilized by 2 different sperm. Each twin has their own amniotic sac and placenta. Genetically these twins will be no more alike than any other siblings. The twins can be 2 boys, 2 girls, or a girl and a boy.
Identical twins: About 33 percent of twins are identical. It means one single fertilized egg splits and develops into 2 babies. Each twin has their own amniotic sac but they may share a placenta (in such instances they are referred to as monochorionic twins). Genetically they will look the same, be the same sex and share the same characteristics and physical traits.
Triplets: These fetuses can be identical, fraternal or even a combination of both.
What Are The Signs Of Having Twins?
Outside of all the regular early signs of pregnancy, women expecting twins may report increased incidences of:
1. Morning sickness: It is suspected that the pregnancy hormone human chorionic gonadotropin (HCG) is the main cause of morning sickness and levels of HCG are higher in women expecting twins. Excessive vomiting can develop into a potentially dangerous condition called hyperemesis gravidarum. Fortunately sickness usually abates by week 12 to 14, even with twins.
2. Exhaustion: Some women report feeling more tired than in previous singleton pregnancies.
3. Weight gain: Your tummy is likely to grow much faster. By the end of the first trimester it is likely to be notably bigger than would be expected for a singleton pregnancy.
4. Back pain in pregnancy: You may notice back pain early in your pregnancy.
5. Heartburn: Many moms expecting twins complain of heartburn in the first few weeks.
6. Pregnancy cramps: Excessive cramping as the uterus (womb) makes room for two babies.
When Do I Find Out If I'm Carrying Twins?
A pregnancy ultrasound scan is the only way to determine if you are expecting twins. You will find out for sure during your first scan which you'll have between weeks 10 and 13. This scan will also date your pregnancy so you will be given an estimated due date. If you are pregnant as a result of in vitro fertilization (IVF) you are likely to receive a scan earlier (about week 6). Sometimes a twin pregnancy is later found to be a singleton pregnancy. This is known as vanishing twin syndrome, for which doctors have no explanation.
When Do I Know If They Are Identical?
Most parents will be curious to know if they are expecting identical or fraternal twins. From a medical point of view the doctor will want to establish whether or not they share a placenta. Although most monochorionic twins are born healthy, up to 15 percent experience twin-to-twin transfusion syndrome (TTTS).This is where one twin receives too little blood and the other too much. Mothers carrying monochorionic are considered high risk, so their pregnancy will be monitored more closely. Your sonographer will establish how many placentas are present in the first trimester ultrasound. If for any reason she is unsure, she will perform a second scan and ask for a second opinion. But even then, the sonographer cannot know for sure if the twins are identical because the placentas of non-identical twins can fuse together.
After The Babies Are Born
When your twins are born and one is a boy and the other a girl, you will know for certain that they are not identical. If they are the same sex and have a placenta each, they may or may not be identical. If they have shared a placenta, and the doctor has examined the placenta carefully and ruled out signs of fusion, you may then discover they are identical. You can also ask for blood tests to be carried out on the umbilical cord of each baby, but this is only usually requested if there are medical reasons to do so. If it is not obvious you can always buy a twin DNA testing kit. Also known as a zygosity test, it requires taking a salvia swab from each baby and sending it to a lab to compare DNA.
What Expecting Twins Means For Mom
Mom can expect:
More frequent prenatal checkups: You will have more frequent checkups with your prenatal healthcare team than were you carrying just one baby (particularly if your babies share the same placenta). You will receive extra ultrasounds, blood pressure tests and weight monitoring. You will also be educated on the early signs of labor.
Nutrition: Your doctor will prescribe a prenatal vitamin - the standard vitamin and dose of folic acid will suffice. You don't need a special 'twin' vitamin. If you are at risk of anemia during pregnancy you may be prescribed an additional iron supplement.
More weight gain: The recommended weight gain for a woman carrying twins is 30 to 35 pounds (and not more than 40 pounds or less than 15 pounds). This compares to 25 pounds weight gain for a singleton pregnancy. You will need to eat a little more than normal, depending on your activity level. The general rule of thumb is to add an additional 300 calories a day to your non-pregnant allowance per baby. So twins require adding 600 calories (probably takes you to about 2,800 calories a day) and triplets require adding 900 additional calories (3,100 calories in total) a day.
Be more careful: Your doctor might ask you to limit some of your activities such as work and travel as your pregnancy progresses. Although bed rest has not proven effective in preventing premature labor, it can encourage fetal growth and reduce complications.
What Complications Are Associated With Twins?
Hypertension during pregnancy
Moms expecting more than one baby are prone to developing high blood pressure during pregnancy. When it occurs with protein in the urine and edema (sudden swelling) this is a dangerous condition called preeclampsia. Careful management of both mother and baby will be necessary.
Why is high blood pressure dangerous?
Will pregnancy raise my blood pressure?
Your babies may be born early for lots of reasons including premature rupture of membranes (PROM), placenta abruption and placental insufficiency. If you show signs of premature labor you may be given steroid injections to speed up the growth of your baby's lungs. In rare instances one baby may be born prematurely while the other continues to grow in the uterus. This is known as delayed-interval delivery.
Twin-twin transfusion syndrome (TTTS)
Also known as Feto-Fetal Transfusion Syndrome (FFTS) and Twin Oligohydramnios-Polyhydramnios Sequence (TOPS). This is where twins share the same placenta, but one receives too much blood and the other too little. It is a serious complication which may prompt doctors to recommend an early delivery.
If you are carrying more than one baby your risk of miscarriage is higher. If a miscarriage is going to happen, it is likely to do so in the first trimester. Sometimes, maybe only one baby is lost. The fetus is (harmlessly) reabsorbed into the mother's body, this is known as vanishing twin syndrome. Vanishing twin syndrome occurs in up to 30 percent of multiple pregnancies. It may even be more common than we think because some mothers never even know they were expecting twins.
Fetal growth restriction
Also, called intrauterine growth restriction. This is where one or both babies do not grow as well as they should. It can cause complications during labor. However many babies, even if they have a low-birth weight are still healthy.
The risk of developing gestational diabetes is higher with twins. The most common complication of gestational diabetes is having larger babies that require c-section delivery. Far less common, there is a slight risk of intrauterine fetal death if the condition is not managed.
The risk of stillbirth is higher with multiple births: 12 per 1,000 twin births; 31 per 1,000 triplet births compared to 5 per 1,000 for singleton births. The risk increases after 38 weeks (and more so after 40 weeks which is termed postmaturity). For this reason, if you have not given birth by week 38 you may be induced. If your twins share the same placenta they may be induced at week 37 if there is no sign of imminent labor.
• PUPPS rash.