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MULTIPLE BIRTHS
Triplets and other higher-order multiple births, such as quadruplets or quintuplets, can be identical, fraternal, or a combination of both. Triplets occur in one in 7,000 births, whereas quintuplets are likely to be born only once in 47 million births.
While these types of births are rare, there has been a rise in the number of triplet and other higher order multiple births over the past two decades. Up from 1,034 births in 1971 to 4,973 for 1995, the 400 percent increase in higher order multiple births (triplets, quadruplets, and quintuplets) reflects the rising number of births to women in their thirties, who are more likely to have a multiple birth, and the use of fertility-enhancing drugs and techniques.
Triplets
Triplets can result from a single fertilized egg that splits three ways to produce three identical individuals (the equivalent of identical twins). They would look the same and all be the same sex. They would be identical triplets, but this is very rare. Most often the mother produces three separate eggs at ovulation, which are then fertilized and become three un-alike individuals - fraternal twins.
Another combination of triplets could result from the mother producing two eggs that are fertilized, and then one of those eggs proceeds to divide in two to produce two identical individuals. This would result in triplets in whom two are identical and the third is a fraternal to the others. You could have two identical girls and a boy, or two identical boys and a girl, or all the same sex, with two being identical.
Quadtruplets
There can be different types of quadruplets just as there are different types of triplets. There can be any combination of fraternals and identicals within the four. Many of the other higher order multiples result from multiple ovulations and thus are fraternal.
Facts about triplet and higher-order births
- More than a third (38.7% in 1996 and 43.3% in 1997) of triplet and higher-order multiple births are attributed to assisted reproduction technology (ART)
- Following the introduction of ART in 1978, the ratio of triplet and higher-order multiple births has more than quadrupled from 37 to 173.6 per 100,000 live births from 1980 to 1997 respectively.
- Pregnancies associated with ART or ovulation inducing drugs are more likely than spontaneously conceived pregnancies to result in multiple births (twins or more). In 1996, 38% of all ART births were multiple births, compared with 3% of births in the general population.
- Compared to singleton births, multiple births - in particular, triplet and higher-order multiple–are associated with greater health risks for the mother and the babies. Risks for the mother include cesarean section and hemorrhage, and risks for the babies include low birth weight (LBW), preterm delivery, and death.
- The average birth weight of a triplet newborn is only half that of a single birth and the period of gestation is usually 7 weeks shorter.
- Infant mortality rates are 12 times higher for these births than for single births.
- Preterm and LBW infants often require costly neonatal care and long-term developmental follow-up.
Multiple Birth Risks
Multiple birth risks include preterm labor resulting in premature births. Single pregnancies generally last about 40 weeks; a twin pregnancy usually lasts 37 weeks. The risk of premature delivery increases with higher-order multiples.
Multiple birth babies are also at risk of extreme jaundice, apnea, anemia, serious infections, gastroesophageal reflux, abnormal growth of blood vessels in the eyes, and respiratory distress due to underdeveloped lungs. In addition, developmental delays and cerebral palsy occur more commonly in multiple births than in single births.
Ultrasounds are generally performed in the last few months of pregnancy in order to follow the growth and developmentof each baby.
Thomas G. Stovall, M.D.
Dr. Stovall is a Clinical Professor of Obstetrics and Gynecology at the University of Tennessee Health Science Center in Memphis, Tennessee and Partner of Women's Health Specialists, Inc.
Date Published: 2004-03-10
7800 Wolf Trail Cove, Germantown, TN 38138
Phone: (901) 682-9222; Fax: (901) 682-9505