More Woes With Infant Boys
Women's problems with the opposite sex begin in the womb because boys -- according to a new study -- cause more complications than girls during labor and delivery.
Male infants require more Caesarean sections and instrument deliveries than girls, cause longer labor, and need more fetal blood samples and hormone stimulation to induce contractions, doctors said yesterday.
Male babies are larger, heavier, leaner and have bigger heads than girls, but Maeve Eogan of the National Maternity Hospital in Dublin said all of that does not explain all the differences. "We don't know what the answer is," she said in an interview.
Eogan and her colleagues studied data on 8,000 deliveries at the hospital between 1997 and 2000. Their research is reported in the British Medical Journal. All the women were carrying their first child and went into labor spontaneously at term.
Molecules' Role in Fertility
In a finding that could lead both to new ways to treat infertility and to new types of contraceptives, scientists have identified molecules that help embryos stick to the wall of the uterus.
Timing is everything, the study found.
By analyzing carbohydrate molecules on the surface of the uterus during different times of the menstrual cycle and identifying a protein, called L-selectin, on the surface of the embryo, researchers at the University of California at San Francisco learned for the first time how the embryo sticks to the wall.
Susan J. Fisher said coatings on the uterus and on the surface of the embryo act like puzzle pieces that touch and quickly lock.
The carbohydrate sugar molecule on the surface of the uterus is secreted for only a short time during a woman's monthly cycle, and the embryo, with its L-selectin coating, must arrive at the uterus during this time.
"It has to take place in exact synchrony or you don't get pregnant," said Fisher, noting that failure to implant on the uterus is a common cause of failed conceptions.
Sharks at Risk of Extinction
Overfishing has driven several species of shark to near extinction in the North Atlantic, researchers in Canada reported.
Populations overall are down 50 percent over the past 15 years, with hammerhead shark populations down 89 percent, Julia Baum and colleagues at Dalhousie University in Halifax, Nova Scotia, said.
"Scalloped hammerhead, white and thresher sharks are estimated to have declined by over 75 percent in the past 15 years," they noted in their report, published in the journal Science.
They analyzed logs kept by fishing boat crews seeking tuna and swordfish -- also heavily hit by fishing -- in the northwest Atlantic between 1986 and 2000. The fishing crews kept a record of every sea creature hooked on their longlines, which have 550 hooks on each line.
"We estimate that all recorded shark species, with the exception of makos, have declined by more than 50 percent in the past 8 to 15 years," they said.
Some areas have no white sharks at all, they reported.
-- Compiled from reports by
the Associated Press and Reuters