Birth rates are climbing after years of significant declines, according to an annual report released Monday in the journal Pediatrics.

Researchers from the Centers for Disease Control and Prevention found that the number of U.S. births for 2007 had jumped 1% to 4,317,119, "the highest number ever registered for the United States," they said. Almost 1.9 million people joined the population due to "natural increase," which is basically the net birth rate. 

As the birth rate rose, the age-adjusted death rate also dropped 2.1%, another record low for the U.S. Life expectancy at birth reached a record high of 77.9 years.

One shocker: The United States' infant death rate is 6.83 per 1,000 births. Compare that with Malaysia (6.2) or Korea (3.8). And in the U.S. capital, the District of Columbia? It's nearly double the national rate, at 12.22.

Younger mothers, particular adolescents, pushed the birth rate higher. From 1991 through 2005, teen birth rates dropped 34%. Since 2005, though, they've popped back up 5%. "The recent increase was preceded by the slowing decline but, nonetheless, caught the public and the public health community somewhat by surprise," the study said.

In terms of teen-pregnancy prevention, the study's authors conclude, "it could be that new messages and strategies are needed to reach the teenagers of today."

-- Amina Khan

Photo credit: iStockphoto.com

When couples with fertility problems turn to IVF, they often assume that they can double their chances for a healthy baby by transferring two embryos to the womb instead of just one.

But new data published in Thursday’s edition of the New England Journal of Medicine shows that what they’re really doing is increasing their odds of having twins – an outcome that is riskier for the mother and babies alike.

In the early days of in vitro fertilization, doctors routinely transferred half a dozen – or more – embryos into a patient’s uterus to boost the odds that at least one would implant and grow into a healthy baby. As the treatment improved, doctors were able to get better results using fewer embryos.

Debate lingers about the pros and cons of transferring two embryos instead of just one. As my colleague Shari Roan reported in the Health section in 2007, pregnancies involving multiples come with a greater risk of gestational diabetes, bleeding and preeclampsia for the mother and cerebral palsy, birth defects, developmental delays and death for the babies. Twins usually survive, but incur much higher medical expenses over the first five years of life.

A team of Swedish researchers is trying to assess the optimum number of embryos to transfer during a cycle of in vitro fertilization. In their study of 661 IVF patients, 331 women got two embryos on their first try, and 142 of them (or 43%) had a live birth. The other 330 women got a single embryo, and if that didn’t work, they made a second attempt with another embryo that had been frozen and thawed. Of these women, 128 (or 39%) had a live birth.

The difference between 43% and 39% wasn’t statistically significant. But one-third of the patients in the double-embryo group had twins or triplets, compared with only 1% of patients in the single-embryo group. Those results were published in the New England Journal of Medicine in 2004.

The research team, from Gothenburg, Sweden, continued to follow those 661 patients through as many as four additional IVF cycles (with no restrictions on how many thawed embryos were transferred at a time). In the latest issue of the journal, they offered the final tally.

Their key statistic is the cumulative live birth rate, which measures the number of patients who wound up with at least one live birth divided by the total number of patients. In the group that started out with a double-embryo transfer, the cumulative live birth rate was 51%. In the group that started out with a single transfer, the rate was 44%. As before, the difference wasn’t statistically significant.

Also as before, the difference in multiples was huge. There were four sets of twins in the single-embryo group (for an overall rate of 2.3%) versus 51 sets of twins and one set of triplets in the double-embryo group (for an overall rate of 27.5%).

The researchers conclude that for IVF patients, there’s little downside and plenty of upside to transferring one embryo at a time instead of two.

-- Karen Kaplan

Photo: Doctors performing in vitro fertilization should transfer only one embryo at a time, according to a new analysis. Photo credit: Liz O. Baylen/Los Angeles Times

Women have had access to home ovulation test kits for years, but more options are becoming available to men to measure their lack, or abundance, of sperm.

In March, the U.S. Food and Drug Administration approved the first at-home test kit for men to use aftera vasectomy to make sure they have achieved sterility. Called SpermCheck Vasectomy, the test measures a protein called SP-10 that is present in each sperm head. The test may be useful because sperm can remain in the male reproductive tract for weeks or months after a vasectomy. Men are advised to follow up with their doctors to determine if the operation was successful. But a study in the British Journal of Urology showed high numbers of patients fail to follow up with their doctors. The kit will be available in drug stores by the end of the year and is available now from doctors or from the manufacturer, ContraVac.

The company also expects to release a home test kit to assess sperm counts for men who are hoping to father a child. A couple of home sperm test kits are already on the market. ContraVac is also developing a test kit that will be used to help evaluate the effectiveness of male contraceptives.

The evolution in assessing male fertility has been aided by 25 years of research by John Herr, a professor of cell biology at the University of Virginia. Herr and his colleagues identified the SP-10 protein.

-- Shari Roan

Photo: John Herr, director of the University of Virginia's Center for Research in Contraceptive and Reproductive Health. Credit: University of Virginia