Triplet births have increased, risks are high, Norwegian researchers say

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The rate of natural triplet births--those not resulting from assisted reproductive technology (ART)--is 2.5 times as high as it was in the 1970s, probably because of the increased use of ovulation-inducing drugs and the older age of mothers, Norwegian researchers reported Wednesday. And despite improvements in prenatal care, the death rate for triplets is about 10 times as high as for a singleton, Dr. Anne Tandberg of the Haukeland University Hospital in Bergen and her colleagues reported in BJOG: An International Journal of Obstetrics and Gynaecology.

The researchers studied the records of more than 2 million pregnancies in the Medical Birth Registry of Norway between 1967 and 2006, examining all live births and stillbirths after the 16th week of gestation. The highest rate of triplet births was 3.5 per 10,000 pregnancies in the five-year period between 1987 and 1991, probably because of the increased used of ART and in vitro fertilization. Following the introduction of new guidelines that called for the implantation of only one embryo during IVF, the number fell to 2.7 per 10,000 and has remained constant at that level.

The mother’s age at birth increased by 2.5 years during the period, while the Cesarian-section rate for triplet pregnancies increased from 46.7% to 92%. The gestational age of triplets at birth fell from 34.1 weeks to 32.1 weeks, accompanied by a fall in the infants’ birth weights

The study found that it is very important to prolong the triplet pregnancy beyond the 28th week of gestation, Tandberg said. Before that milestone, the mortality rate is 50%, but beyond it the rate falls to 3.8%.

-- Thomas H. Maugh II