MORE LEFT HANDED MEN ARE BORN DURING THE WINTER

Men born in November, December or January are more likely of being left-handed than during the rest of the year. While the genetic bases of handedness are still under debate, scientists at the Faculty of Psychology, University of Vienna, obtained indirect evidence of a hormonal mechanism promoting left-handedness among men.

Psychologist Ulrich Tran and his colleagues published their findings in the scientific journal Cortex.

Various manual tasks in everyday life require the use of the right hand or are optimized for right-handers. Around 90 percent of the general population is right-handed, only about 10 percent is left-handed. The study of Ulrich Tran, Stefan Stieger, and Martin Voracek comprised two large and independent samples of nearly 13,000 adults from Austria and Germany. As in modern genetic studies, where a discovery-and-replication-sample design is standard, the use of two samples allowed testing the replicability and robustness of findings within one-and-the-same study.

Overall, 7.5 percent of women and 8.8 percent of men were left-handed. "We were surprised to see that this imbalance was caused by more left-handed men being born specifically during November, December, and January. On a monthly average, 8.2 percent of left-handed men were born during the period February to October. During November to January, this number rose to 10.5 percent," according to Ulrich Tran, lead author of the study.

A hormonal cause during embryonic development

"Presumably, the relative darkness during the period November to January is not directly connected to this birth seasonality of handedness. We assume that the relative brightness during the period May to July, half a year before, is its distal cause," explains Ulrich Tran. A theory, brought forth in the 1980s by US neurologists Norman Geschwind and Albert Galaburda, posits that testosterone delays the maturation of the left brain hemisphere during embryonic development. The left brain hemisphere is dominant among right-handers, the right brain hemisphere is dominant among left-handers. Intrauterine testosterone levels are higher in the male fetus, because of its own testosterone secretion, than in the female fetus. However, the testosterone level of the mother and external factors may also affect intrauterine testosterone levels. Specifically, more daylight may increase testosterone levels, making a seasonality effect plausible.

Previous studies on the subject provided mixed and inconsistent evidence. There was no clear indication which season has an effect, and whether seasonality affects men, women or both sexes equally. According to the current findings, there is a small, but robust and replicable, effect of birth seasonality on handedness, affecting only men. These results are consistent with a hormonal basis of handedness, corroborating thus an old and controversial theory. However, the exact way of causation needs to be investigated in future studies.

WORLDS FIRST CHILD BORN AFTER UTERUS TRANSPLANTATION

In a ground-breaking research project at the University of Gothenburg, seven Swedish women have had embryos reintroduced after receiving wombs from living donors. Now the first transplanted woman has delivered a baby -- a healthy and normally developed boy. The world-unique birth was acknowledged in The Lancet on 5 October.

The uterus transplantation research project at the University of Gothenburg started in 1999 and has been evaluated in over 40 scientific articles. The goal of the Gothenburg project is to enable women who were born without a womb or who have lost their wombs in cancer surgery to give birth to their own children.

Live donors

Nine women in the project have received a womb from live donors -- in most cases the recipient's mother but also other family members and close friends. The transplanted uterus was removed in two cases, in one case due to a serious infection and in the other due to blood clots in the transplanted blood vessels.

The seven remaining women have in 2014 tried to become pregnant through a process where their own embryos, produced through IVF, are reintroduced to the transplanted uterus.

First child from a transplanted uterus

The first early pregnancy was confirmed in the spring after a successful first pregnancy attempt in a woman in her mid-30s, a little over a year after her transplantation.

In early September, the woman successfully delivered a baby by caesarean section, making her the first woman in the world to deliver a child from a transplanted uterus. Her uterus was donated by a 61-year-old unrelated woman.

The caesarean section had to be performed earlier than planned: the woman developed preeclampsia in week 32 of her pregnancy and the CTG indicated that the baby was under stress. A caesarean section was performed in accordance with normal clinical routines so as not to risk the health of the mother and child.

Developing normally

According to Professor Mats Brännström, who performed the caesarean section, the perfectly healthy newborn boy is developing normally. The baby weighed 1,775 grams (3 lbs 14.6 oz) at birth, which is normal size considering the gestational age at delivery.

'The baby screamed right away and has not required any other care than normal clinical observation at the neonatal unit. The mother and child are both doing well and have returned home. The new parents are of course very happy and thankful,' says Professor Mats Brännström, who is leading the research project.

'The reason for the woman's preeclampsia is unknown, but it may be due to her immunosuppressive treatment combined with the fact that she is missing one kidney. The age of the donated womb may also be a factor. Also, preeclampsia is generally more common among women who have become pregnant through IVF treatment.'

Mild rejection episodes

The woman has had three mild rejection episodes since the transplant, one of which occurred during the pregnancy. The rejection episodes, which are often seen also in other types of transplants, could be stopped with immunosuppressive treatment.

Followed closely

The research team followed the pregnancy closely, carefully monitoring the growth and development of the foetus with a special focus on the blood supply to the uterus and umbilical cord.

'There were concerns that the blood supply may be compromised since we had reattached the blood vessels to the womb. But we did not notice anything unusual concerning the function of the uterus and the foetus, and the pregnancy followed all normal curves,' says Brännström.

Major step

The successful delivery is considered a major step forward.

'It gives us scientific evidence that the concept of uterus transplantation can be used to treat uterine factor infertility, which up to now has remained the last untreatable form of female infertility. It also shows that transplants with a live donor are possible, including if the donor is past menopause,' says Brännström.

Several research teams around the world have been awaiting the results of the Gothenburg study in order to launch similar observational studies. The pregnancy attempts are ongoing with the other six women in the project.