Multiple Pregnancy - Twins, Triplets

When a woman becomes pregnant, the process of conception does not always stop at one baby. A pregnancy of more than one fetus concurrently is called a multiple pregnancy. While the majority of multiple pregnancies refer to twin/triplets, with the increase in the use of fertility drugs, multiples have been growing in number in recent years.

There are various situations that may lead to the conception or growth of a multiple pregnancy. For the sake of discussion, the twin/triplet pregnancy is easiest to understand.

When a female releases more than one egg, when she ovulates twice or she ovulates threee times two/three eggs and all eggs are fertilized, dizygotic twins/trizygotic triplets  (fraternal or nonidentical) twins/triplets are created. On the other hand if one egg is released with only one sperm fertilizing the egg and the egg then splits into multiple embryos monozygotic or maternal/identical twins/triplets are created.

How Twins/Triplets Develop
Dizygotic or Fraternal twins/triplets are the most common form of twin/triplet birth. They happen when separate eggs are fertilized by separate sperms. The incidence of dizygotic twins depends on the woman's ethnic backgroud. Africans have a higher incidence, Caucasians are somewhere in the middle, and Asians have the lowest incidence. Contrary to common belief, fraternal twins/triplets do not have to be of opposite sexes. Fraternal twins/triplets can have differing blood types, hair color, eye color and even body type upon birth. All dizygotic fraternal twins/triplets will have different amniotic sacs and, most often, different placentas.

Monozygotic or identica/maternall twins/triplets are far less likely to occur based on the fact that the single egg splits into two or three embryos during the first stage of development. The incidence of spontaneous monozygotic twins is the same all over the world about 1 in 250 pregnancies, though it increases if the pregnancy was achieved with IVF in-vitro fertilization. Identical twin/triplets may share a placenta or an amniotic sac or they may have separate placentas and sacs. All identicals will have the same blood type, hair color, eye color and sex. Contrary to common belief, identicals do not have the same fingerprints or always the same DNA. Monozygotic twins can have two different outer and inner sacs (Dichorionic/Diamniotic), one outer and two inner sacs (Monochorionic/Di amniotic), or they can both be in the same sac (Mono/Mono). Twins that share the same outer sac are at increased risjk for certain complications because they can share blood vessels.

Extra Special Care
When a multiple pregnancy is discovered, the mother to be will most often be termed a high risk pregnancy. This is due to the fact that the body is created to hold only one baby per pregnancy. When the weight of the baby reaches a certain level, childbirth begins. In multiples pregnancies, childbirth can begin too early due to the increased weight and stress on the body, thus the high risk term.

High risk pregnancies will often require additional testing and routine checkups. Depending on whether the pregnancy is a twin or triplet pregnancy, bed rest may be ordered as early as the first trimester. The increased weight of the multiple fetuses can cause the mother to go into early labor before the 37^th week of pregnancy which is considered the first week of full term status.

When mothers of multiples go into labor too early, prescription medications may be used to control contractions of the uterus. If oral medications are not effective, hospitalization and an intravenous solution may be needed to stop contractions for as long as possible. The longer the fetuses spend in-utero, the more developed the babies will be upon birth. Many obstetricians aim for at least 34 weeks in multiple pregnancies. Babies born before the 37^th week will be considered preterm or premature and may require specialized care in the Neonatal Intensive Care Unit before being released to go home from the hospital.