Swamp wallabies, which stand about 2 feet (70 centimeters) tall, are native to eastern Australia, where they live in forests and swamps. They become sexually mature at 15 months old, can breed year-round and have a gestation period that lasts 33 to 38 days, according to the University of Michigan’s Museum of Zoology.However, the wallabies’ estrus cycle is only 31 days long, scientists wrote in the new study, published online March 2 in the journal Proceedings of the National Academy of Sciences. Mammalian reproduction includes four stages: ovulation, fertilization, pregnancy and lactation. In a group of marsupials called macropodids, حوامل which includes kangaroos and wallabies, certain species experience ovulation shortly after birth — sometimes within hours, the study authors wrote. Because swamp wallabies’ estrus cycle is shorter than their gestation period, researchers had long suspected that mating and conception for these animals might overlap with pregnancy.To find out if that was the case, scientists with Australia’s University of Melbourne and the Leibniz Institute for Zoo and Wildlife Research in Berlin collected vaginal smears and conducted high-resolution ultrasounds of pregnant wallabies.They found that 90% of the pregnant females were actually doubly pregnant, carrying a second embryo fertilized from ovulation that took place when their full-term fetus had already completed 97% to 100% of its gestation.But the fetuses weren’t womb-mates. Marsupial females have twin uteri (along with three vaginas). This means that a pregnant swamp wallaby, days away from delivering a fetus in one uterus, can ovulate, mate and develop a newly fertilized embryo in her second uterus.However, that second fetus doesn’t start developing yet, according to the study. Marsupials deliver their young at a much earlier developmental stage than other mammals, and their joeys have months of lactation and growth ahead of them. While the newborn is nursing the embryo is “paused” in the womb, and its development doesn’t begin until lactation of its sibling ends and the baby leaves their mother’s pouch.These results clearly demonstrate that the swamp wallaby conceives a new embryo before birth,” the scientists wrote. This reproduction strategy “completely blurs the normal staged system of reproduction in mammals.”
Men who smoke marijuana may have a better chance of having a baby with their female partner, compared with those who don’t use the drug, a surprising new study suggests. In contrast, couples whose male partner said he currently used marijuana had better chances of having a child, compared with couples whose male partner didn’t currently use marijuana.This finding was unexpected, according to the authors, from the Harvard T.H. Chan School of Public Health in Boston. The researchers had hypothesized that marijuana smoking wouldn’t be related to fertility outcomes in either men or women, as has been the case in previous studies. But the new result agrees with findings in an earlier study from the same group of researchers. In that study, men who reported ever having smoked marijuanaon average, than those who had never used the drug. Still, the new findings don’t mean that men should start smoking marijuana to boost their fertility. Only a small number of participants said they smoked marijuana around the time of their fertility treatments, which reduces the strength of the results. At most, they suggest that marijuana may not have a harmful effect on men’s fertility, the authors said. On the other hand, the researchers don’t think their findings should be taken as evidence that marijuana has a beneficial effect for men undergoing There is an urgent need for “additional research to clarify the role of marijuana use on human reproduction and on the offspring’s health,” the authors concluded.Despite the growing use and around the world, scientists know little about how the drug impacts fertility. And few studies have included both men and women.In the new study, the researchers analyzed information from 200 couples who underwent fertility treatment at Massachusetts General Hospital between 2005 and 2017. The researchers also included data from an additional 220 women who underwent fertility treatment, but did not have a partner in the study.