Pregnancy Risks and Fertility Gene

Magnesium sulfate lowers eclampsia risk, smoking could mean less boys being born

Anticonvulsant For Eclampsia

PARIS

    Magnesium sulfate, a cheap and to all evidence safe anticonvulsant drug, can dramatically protect pregnant women at risk from eclampsia, according to a study published last May The Lancet. The study, led by the Institute for Health Sciences in Oxford, England, included 10,000 women from 33 countries with preeclampsia who were either randomly assigned magnesium sulphate or a dummy treatment.

    Magnesium sulfate reduced the risk of eclampsia by 58 percent and the risk of maternal death during pregnancy by 45 percent. The drug proved to be so conclusively successful that the trial was scrapped while it was still in its early stages. Magnesium sulfate was first used in obstetric care in the United States nearly a century ago but its effectiveness had never been assessed on a wide scale.

    Preeclampsia affects between five and eight percent of pregnancies and accounts for around 50,000 maternal deaths each year.

Pool Danger

PARIS

    Pregnant women who go for a swim or antenatal exercise in their pool may be exposed to high levels of chemicals that have been linked to miscarriage and fetal damage, according to a study in the Occupational and Environmental Medicine, a journal of the British Medical Association.

    Samples taken from eight indoor swimming pools in London were found to have relatively high levels of chlorine by-products called trihalomethanes (THMs), it said. THMs are created when chlorine, added to pool water and also tap water to kill infection-causing bacteria, reacts with organic matter such as sweat, dust, skin cells, and body-care products. High levels of THMs have been previously implicated with miscarriage, low birthweight, and fetal spine deformation.

    The study found that total organic matter in pool water was three times higher than in tap water. Levels of chloroform, the most common THM classified as a potential cancer agent, were 20 times higher. THM concentrations rose when the pool temperature was higher and when there were more swimmers in the pool.

    The researchers did not make any direct link between swimming and health problems for pregnant women and their unborn child. But they said they feared swimming pools with high chemical concentrations "could be a major pathway" for exposure to THMs and further research was needed to evaluate any threat.

    Previous research has indicated that a one-hour swim gives a chloroform dose 141 times higher than a 10-minute shower. This is because THMs vaporize into the atmosphere, which means that they can be breathed in by a swimmer as well as ingested through swallowing or absorbed through contact with the skin.

Want a boy? Don't smoke

PARIS

    Couples who smoke during the period of conception may be substantially reducing their chances of having a boy, according to a study in The Lancet. Such a link between smoking and reduced male births could seriously alter the ratio between males and females in Asia, where smoking among men is widespread.

    Dr. Misao Fukuda of Japan and his Japanese and Danish colleagues chronicled the sex of more than 11,000 births at his clinic between December 2000 and July last year. They interviewed 5,372 mothers regarding their and their partners' smoking habits in the period beginning three months prior to conception until they found out they were pregnant.

    Of those where neither partner smoked, the study found that 121 boys were born for every 100 girls, a figure that fell to only 82 boys per 100 girls for those parents who smoked more than 20 cigarettes a day. Moreover, there was also a marked fall in male births when only the father smoked with the study reporting a figure of 98 male births for every 100 females.

    The doctors believe that the reduced male births among smoking parents could be attributed to the greater susceptibility of "Y" chromosomes-which determine the male sex-to toxic substances than those of "X" chromosomes, the female determinant.

    "Our working hypothesis is that the sperm cells carrying the Y-chromosome are more sensitive to unfavorable changes caused by smoking than sperm cells with an X-chromosome," Prof. Anne Grete Byskov of the University of Copenhagen, said.

    "In our study, the number of fathers who smoked during the periconceptional period was sufficiently large to show that paternal smoking significantly reduced the sex ratio," wrote the authors.

    The findings could have wide implications for the world's population ratio, with more than two-thirds of adult men in China, being regular smokers. Smoking will account for one in three of all premature deaths among Chinese men in the years ahead unless action is taken to prevent a medical catastrophe.

Fertility Gene

WASHINGTON

    Researchers in the United States have identified an ovarian gene that could regulate fertility in women. Researchers at the National Institute of Child Health and Human Development believe the gene could play a role in premature ovarian failure, which affects certain women older than 40 who have not reached menopause.

    The work of Dr. Zhi-Bin Tong and his colleagues, published in Human Reproduction, "could lead to new insights into the causes of unexplained infertility in women," said Duane Alexander, director of the institute.

    The same researchers had earlier identified a gene in female mice they called "Mater," which helps to produce a protein essential to the development of a fertile ovary. Without this gene, the mouse ovary cannot survive beyond the first cell division. In the most recent study they have identified a human gene that appears to be the same as "Mater," with 67 percent of its DNA identical to that in female mice.

    "If the human gene is found to serve the same function as the mouse gene, it may result in a new approach to the study and treatment of female infertility," said Lawrence Nelson, co-author of the study.

Age-Breast Cancer Link

PARIS

    Women who have a child late in life face a much higher risk of developing breast cancer, according to a major study published in Cancer, the organ of Britain's Cancer Research Campaign.

    The study, which involved 91,260 Frenchwomen whose health was monitored from 1990 to 1997, also said that girls who start their periods relatively late in their teenage years enjoy a reduced risk of developing breast cancer later in life. A total of 1,718 were diagnosed with breast cancer during this period.

    Women who had their first child in their thirties were 63 percent more likely than women who gave birth before 30 to develop breast cancer before the menopause. And they had a 35-percent higher risk of developing breast cancer after the menopause.

    Girls who began menstruating at 15 were a third less likely to develop breast cancer than girls who had their first period before the age of 12. "Our results suggest that reproductive events have complex effects on the risk of breast cancer," the authors of the report said.

    Previous studies have indicated that immature breast cells are relatively easily infiltrated by carcinogens, sometimes causing a tumor to develop several years later. In pregnancy, however, breast cells mature very quickly during the third trimester, and this makes them less sensitive to carcinogenic triggers.

The Pill And Infection

PARIS

    Women who have a common genital infection called the human papillomavirus (HPV) and are long-term users of the Pill face three times greater risk of cervical cancer, says a study of 1,900 women in Brazil, Colombia, Morocco, Peru, the Philippines, Spain, and Thailand who were either healthy or were treated for cervical cancer.

    Ninety-four percent of women with invasive cervical cancer, and 72 percent who had cervical carcinoma, had HPV or genital warts. Women who tested positive for HPV and who used oral contraceptives for between five and nine years were around three times likelier to have cervical cancer than those who did not take the Pill. Those who had been using the Pill for 10 years or more faced a fourfold risk. But there was no evidence that long-term use boosted the risk of cancer in the absence of HPV.

    The research was carried out by a specialist unit on cervical cancer of the International Agency for Research on Cancer (IARC) in Lyon, France. IARC specialist Silvia Franceschi said the results pointed to a clear link between the Pill and HPV. "Long-term users of oral contraceptives should be included in cervical screening programs," she said.

    The IARC report said that women who had HPV and had many children also faced a higher risk of cancer of the cervix. Women who had seven or more life births were nearly four times likelier to have cervical cancer than childless women. Sexually active women, especially those with HPV, are generally advised to undergo a "pap" test every year to identify any suspect cells on the cervix.