THURSDAY, Feb. 4 (HealthDay News) -- Researchers say they've discovered genetic traits in mothers and fetuses that appear to boost the risk of premature labor and delivery.

The traits are found in genes that regulate inflammation -- the immune system's response to invaders -- and the material that holds cells within tissues.

"A substantial body of scientific evidence indicates that inflammatory hormones may play a significant role in the labor process," Dr. Alan E. Guttmacher, acting director of the U.S. National Institute of Child Health and Human Development, said in an agency news release. "The current findings add evidence that individual genetic variation in that response may account for why preterm labor occurs in some pregnancies and not in others."

Researchers report that the findings could help doctors discover which women are at most risk for premature birth and then be able to help them postpone delivery until an appropriate time.

The findings were to be presented Thursday in Chicago at the annual meeting of the Society for Maternal-Fetal Medicine.

According to the researchers, premature birth can cause a long list of problems, ranging from blindness and learning disabilities to death.

For the study, they analyzed genes from 229 women and 179 premature infants in Chile. All of the women were Hispanic.

More information

The U.S. National Institute of Child Health and Human Development has more on premature labor and birth.

TUESDAY, Feb. 2 (HealthDay News) -- In a study that highlights the growing crisis of birth-acquired HIV in teens and young adults, new research has found that nearly 50 percent of youths aged 10 to 18 who were admitted to two public hospitals in Zimbabwe were infected with HIV, the virus that causes AIDS.

The HIV-positive adolescents were more likely to have stunted growth, delayed puberty and to have a mother who was infected with HIV or who had died of AIDS, the study found.

The researchers said that 69 percent of HIV-positive adolescents were admitted to the hospital because of infections, such as tuberculosis or pneumonia, compared with 19 percent of youths who did not have HIV. Also, 22 percent of the HIV-infected youths and 7 percent of the HIV-negative youths died while hospitalized.

The study is published online in the February issue of PLoS Medicine.

Few studies have examined the prevalence of birth-acquired HIV in older children and adolescents, Glenda Gray, of the perinatal HIV unit at the University of Witwatersrand in South Africa, wrote in an accompanying commentary. Gray said this might be because it was believed that children infected with HIV at birth were unlikely to survive beyond age 5.

More information

The U.S. National Institute of Allergy and Infectious Disease has more about children with HIV.

FRIDAY, Jan. 29 (HealthDay News) -- Genital herpes frequently reactivates throughout the genital tract, a finding that may help improve treatment and prevention, U.S. researchers say.

Over 30 days, the investigators collected daily samples from seven separate genital sites in four women infected with herpes simplex virus type 2 (HSV-2). HSV-2 was detected on more than one area on 56 percent of days when there was viral shedding and on genital surfaces on both sides of the women's bodies on most days when HSV-2 was detected at more than one site, according to the researchers at the University of Washington and the Fred Hutchinson Cancer Research Center in Seattle.

The study authors noted that both symptomatic and asymptomatic reactivations were often widely spaced throughout the genital tract, often on both sides of the body, although typically, clinical lesions tend to emanate from one area of the body.

The findings were released online in advance of publication in the Feb. 15 print issue of the Journal of Infectious Diseases.

The researchers said their findings may help lead to the development of a comprehensive treatment that suppresses and limits the transmission of HSV-2 infection.

Currently, genital herpes caused by reactivation of HSV-2 is generally treated as a lesion in one specific genital area.

More information

The U.S. Centers for Disease Control and Prevention has more about genital herpes.

THURSDAY, Jan. 21 (HealthDay News) -- Scientists say they boosted the success of in vitro fertilization in mice by gently rocking embryos before implanting them into the womb.

No evidence yet proves that the same technique would work with human embryos, but authors of a new study hope it might do just that.

"By making the cells feel more at home, we get better cells, which is key to having better infertility treatment," said study co-author Shu Takayama, an associate professor in the University of Michigan's department of biomedical engineering.

The idea of the research is to mimic the motion that an embryo feels traveling through the fallopian tube to the uterus. Human embryos created with the assistance of in vitro fertilization don't get the benefit of such exposure.

The mouse embryos that underwent the rocking treatment with the help of a specially designed device were healthier after four days and had more cells than those grown in dishes. About 77 percent of them resulted in pregnancies when implanted into female mice, compared to 55 percent of those grown in the petri dishes.

The report was published online in the journal Human Reproduction.

Clinical trials of the rocking device have begun in humans through a company formed by the study authors.

More information

The American Pregnancy Association   has more on in vitro fertilization.