Some types of assisted reproductive technologies used in cases of infertility are yielding more boys than girls. Researchers in Australia have published their findings in BJOG: An International Journal of Obstetrics and Gynaecology.
They studied all live births following fertility treatment in Australia and New Zealand from 2002 to 2006. During that period over 13,000 babies were born to women who underwent single embryo transfer (SET) at infertility regulated clinics.
Researchers looked specifically at two different types of ART: in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI). They also considered the stage of embryo development at the time of transfer and whether the egg was fresh or frozen. Since sex selection is banned in Australia, it was the best place to do a secondary sex ratio (SSR) study.
The concern of researchers is that, as the number of babies from ART increases, there may be an imbalance in the sex ratio caused by the technology. This could lead to a serious dilemma for future generations.
Overall, they discovered it’s pretty balanced. For SET, boys are 51.3% which is the same as the Australian average from spontaneous conceptions. However, for ICSI births it goes down to 50% and for IVF it increases to 53%. With some other variables, it goes as high as 56.1%.
“This is the first nation population-based study to assess the impact of ART procedures and treatment practices on the human sex ratio at birth. The results from this study demonstrate that a particular ART procedure or treatment course can alter the probability of having a male baby from the natural sex ratio at birth in Australia of about 51.5% to a low of 48.7% or a high of 56.1% depending on the procedure used. This study provides impetus for further research into the underlying causes and or associations which determine the survival of different sexes of embryos or conceptuses in pregnancy,” said Jishan Dean, co-author of the study School of Women’s and Children’s Health at the University of New South Wales.
There definitely seems to be something influencing the sex and unlocking that mystery would be an important breakthrough.
Source: Royal College of Obstetricians and Gynaecologists, Medical News Today
