The rate of multiple births has jumped, according to the March of Dimes, with the rate of twins increasing 70 percent between 1980 and 2004. Some factors in this increase are due to delayed childbearing and the increase in fertility treatments. For some women, multiple births are common in their family. For other women, the doctor cannot find any factor that explains their multiple pregnancy. Whatever the factors, a twin pregnancy increases complications for the mother and for her babies.
There are two common types of twins–fraternal and identical.
Two-thirds of all twins are fraternal. Fraternal twins are caused when the mother ovulates two separate eggs that are then fertilized by two separate sperm. The babies have separate amniotic sacs and placentas. Fraternal twins can be two boys, two girls or boy/girl twins. Contrary to the plots of books, plays and movies, fraternal twins are no more alike than other siblings are. Fraternal twins often “run” in families.
One third of twins are identical. Identical twins occur when a newly fertilized egg splits in half. These babies share a placenta and generally do not share the same amniotic sac, although in rare cases they can share one sac, according to the Mayo Clinic. All their genetic markers are the same; the babies are the same sex and look exactly alike. Identical twins are not hereditary.
There are three rare types of twins.
Half-identical twins occur when an egg splits and then is fertilized by two sperm. These twins share 75 percent of their genetic markers and can be either same sex or boy/girl twins.
Twenty-five percent of all identical twins are “mirror” identical. Mirror identicals occur when a fertilized egg divides later than typical for identical twins. These babies look alike, but they mirror each other–the natural part in their hair, one baby is left handed and the other right handed. In some rare cases, their internal organs are located on opposite sides.
Conjoined twins occur when the fertilized egg does not completely divide. The babies share some part of their body and sometimes they share one or more internal organs.
Signs of Twin Pregnancy
Although most mothers–and their doctors–will not suspect twins early in their pregnancy, there are some signs a woman might be carrying twins. If the woman has a history of fraternal twins in her family, her chances for multiples are increased. Another sign is if her uterus is larger than it should be for the time in her pregnancy. The use of fertility drugs increases a woman’s ability to conceive twins. Increased hormones due to a multiple pregnancy can cause extreme nausea and vomiting.
With the increase in prenatal care, fewer twin pregnancies are diagnosed on the delivery table. Although some of the blood tests a mother receives during prenatal care might suggest a multiple pregnancy, only an ultrasound can confirm twins.
Because a twin pregnancy puts additional strain on the mother’s body, it is considered high risk. For the mother, twin pregnancy complications include high blood pressure, anemia, excessive vomiting, preterm labor and excessive bleeding after delivery. Complications for the twin babies can include lower birth weight, underdeveloped due to pre-term delivery, birth defects or even death of one baby.
Multiple Prenatal Care
Although each pregnancy is different, once twins are diagnosed, the doctor will monitor the mother-to-be more closely. Since she is carrying two babies, a mother’s diet and weight gain would be different from a mother who is just carrying one child. The recommended weight gain for mothers of twins is 35 to 45 lbs. The doctor might restrict the mother’s activities and travel. In some cases, a doctor might prescribe increased or complete bed rest or even hospitalization for the mother.
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