Twins can be the same (identical-monozygotic) or different (fraternal-dizygotic). Fraternal twins, triplets, or more develop when two or more eggs are fertilized by separate sperm. Fraternal fetuses have separate placentas and amniotic sacs (the bag containing the fluid around a baby).

Identical twins come from a single egg that has been fertilized by one sperm. For unknown reasons, the fertilized egg splits into two or more embryos during the first stage of development. Some identical twins share the same placenta. However, they usually grow within separate amniotic sacs in the uterus. In rare cases, identical twins share one amniotic sac (monoamniotic).

Fraternal multiples:
1. Can be of different sexes and may have different blood types.
2. They may look very different from one another, with different-colored hair and eyes. They may also look alike, as siblings often do.
3. Tend to run in families.
4. They are more common in older mothers, African races and when there is a family history of twins. They are least common in Asian families. If you have already carried fraternal twins, you have double the usual risk of having twins. A history on your partner’s side of the family does not increase your risk of multiple pregnancy.

Identical twins
1. Are always the same sex and blood type.
2. They do not necessarily look exactly alike. One may be right-handed while the other is left-handed.
3. They develop at random. They are not related to maternal age, race, or family history of twins.
4. Multiples that are conceived with infertility treatment are usually fraternal, rather than identical.

What are the causes of multiple pregnancy?
1. With increasing maternal age the chance of twins increases. To put it in perspective, your chance of giving birth to twins if you are less than 25 years of age is less than half of what it would be after the age of 35.
2. You are more likely to conceive twins in the first few menstrual cycles after stopping birth control pills.
3. Infertility treatment. Fertility drugs stimulate your ovaries to release multiple eggs, which can be fertilized at once. This may result in a multiple pregnancy. You are, therefore, more likely to have a multiple pregnancy if you use fertility drugs or assisted reproductive technology (ART - In Vitro Fertilization IVF).
4. ART is the transfer of embryos directly into the uterus. In the early days, when success rates were extremely low, several embryos were transferred in the hope of achieving a pregnancy. Nowadays, 25% to 30% of pregnancies from ART are twins; 5% are triplets and less than 1% are quadruplets or more. As techniques have improved, success rates from IVF/embryo transfer have increased and reasonable success rates are being achieved with single embryo transfer and this reduces the incidence of multiple pregnancies.

What is the prevalence of multiple pregnancy? The natural incidence of twins is 1 in 80 pregnancies and for triplets 1 in 8000 pregnancies. The incidence is rising as a result of IVF and a tendency for women to deliver later in their reproductive years. Naturally occurring quadruplet births occur in 1 per 600,000 births. The UK would, therefore, expect one set of naturally occurring quadruplets each year. There are estimated to be approximately 125 million human twins and triplets in the world, and just 10 million identical twins. One in two pregnancies with same sex babies are monozygous (identical twins). The rate of identical twins remains at about 1 in 333 pregnancies across the globe.

by David Viniker
David A Viniker MD FRCOG is a London Consultant in OB/GYN who strongly supports patient choice. You are welcome to visit his websites which explain the pros and cons of the various options for women’s health, pregnancy and childbirth: www.2womenshealth.com

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A miscarriage is the natural end of pregnancy when the developing embryo or fetus is less than 20 weeks old and incapable of surviving outside the womb. Miscarriages that occur less than six weeks after your last menstrual period are referred to as an ‘early pregnancy loss’, whereas miscarriages that occur after this point are termed ‘clinical spontaneous abortion’. If you are less than six weeks pregnant, you may not even realize you have been so, and may mistake the miscarriage for a heavy menstrual bleed.

More than three-quarters of all miscarriages occur in the first twelve weeks (also known as the first trimester) of your pregnancy. The causes of miscarriage in this first trimester are mostly because of chromosomal abnormalities. As expectant parents, you need to understand that such abnormalities occur at random and are unlikely to occur in future pregnancies. Sometimes a miscarriage in the first trimester can be due to a deficiency of the hormone progesterone. In future pregnancies, your doctor will prescribe a progesterone supplement to ensure your pregnancy proceeds as normal.

Miscarriages in the second trimester are generally related to problems with your uterus, placenta or cervix. Malformations in the umbilical cord can also cause a clinical spontaneous abortion.

While the large proportion of miscarriages are beyond your control, there are several risk factors for miscarriage. Among them are:

1. If you are pregnant with twins, there is a greater chance of early pregnancy loss.
2. If you are a diabetic who does not control your diabetes, there is a considerably heightened risk of miscarriage.
3. Cigarette smoking, whether by you or your partner, increases the chance that your baby may not make it to term.
4. Physical trauma, such as falls or blows, especially to your abdomen may also result in a miscarriage.
5. Excessive caffeine or alcohol intake, obesity and exposure to certain chemicals will also enhance the likelihood of miscarriage.

The most obvious sign of miscarriage is bleeding. If you notice unusual bleeding during your pregnancy, you will need to talk to your doctor, who may perform an ultrasound scan to visualize your developing baby. In many cases, when a miscarriage occurs, your doctor may wish to undertake a procedure known as a curette. A curette ensures that all the baby’s tissue is removed from your uterus, thereby preventing infection and scarring. After a miscarriage, your doctor will want to investigate why the miscarriage occurred and may recommend that you wait several menstrual cycles before attempting to become pregnant again.

Although the physical effects are usually mild, the emotional pain that you and your partner may experience can be quite severe. There is a natural tendency to blame yourself for somehow causing the miscarriage, although in many cases you will have had no control over or effect upon the health of your developing baby.

Your feelings of grief and loss may be very strong, so do not be afraid to seek counseling to help you and your partner through this difficult time. In many instances, there will be no reason for you not to become pregnant in the future, and every likelihood that the pregnancy will proceed smoothly.

About the author:
Juzaily Ramli and his wife are the owners of Pregnancy Website. Find out why miscarriage is a living nightmare amongst the expecting parents at miscarriage website.

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