Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Pitt study notes decline in male births in the US and Japan

11.04.2007
A study published in this week’s online edition of Environmental Health Perspectives reports that during the past thirty years, the number of male births has decreased each year in the U.S. and Japan.

In a review of all births in both countries, the University of Pittsburgh-led study found significantly fewer boys being born relative to girls in the U.S. and Japan, and that an increasing proportion of fetuses that die are male. They note that the decline in births is equivalent to 135,000 fewer white males in the U.S. and 127,000 fewer males in Japan over the past three decades and suggest that environmental factors are one explanation for these trends.

“The pattern of decline in the ratio of male to female births remains largely unexplained,” said Devra Lee Davis, Ph.D., M.P.H., lead investigator of the study, director of the University of Pittsburgh Cancer Institute’s Center for Environmental Oncology and professor of epidemiology, University of Pittsburgh Graduate School of Public Health. “We know that men who work with some solvents, metals and pesticides father fewer baby boys. We also know that nutritional factors, physical health and chemical exposures of pregnant women affect their ability to have children and the health of their offspring. We suspect that some combination of these factors, along with older age of parents, may account for decreasing male births.”

Dr. Davis explained that environmental factors, such as prenatal exposure to endocrine- disrupting environmental pollutants may impact the SRY gene – a gene on the Y chromosome that determines the sex of a fertilized egg. Other environmental factors that also may affect the viability of a male fetus include the parents’ weight, nutrition and the use of alcohol and drugs.

In the study, Dr. Davis and her colleagues reported an overall decline of 17 males per 10,000 births in the U.S. and a decline of 37 males per 10,000 births in Japan since 1970. They also found that while fetal death rates have generally decreased, the proportion of male fetuses that die has continued to increase. In Japan, among the fetuses that die, two-thirds are male, up from just over half in 1970.

The study also examined the ratio of African-American male to female births to that of whites in the U.S. The researchers found that while the number of African-American male births has increased modestly over time, the ratio of male to female births for African-Americans remains lower than that of whites. In addition, they noted that African-Americans have a higher fetal mortality rate overall and a higher proportion of male fetuses that die.

“These results are not surprising since the black-white ratio in terms of infant mortality has remained the same for almost 100 years,” said Lovell A. Jones, Ph.D., study co-investigator and professor and director, Center for Research on Minority Health, department of health disparities research, University of Texas M.D. Anderson Cancer Center. “Given the higher mortality rates for African-American males in the United States, these results reemphasize the need to determine all factors, including environmental contaminants, which are responsible for this continuing health disparity.”

“Given the importance of reproduction for the health of any species, the trends we observed in the U.S. and Japan merit concern,” added Dr. Davis. “In light of our findings, more detailed studies should be carried out that examine sex ratio in smaller groups with defined exposures as a potential indicator of environmental contamination.”

Clare Collins | EurekAlert!
Further information:
http://www.upmc.edu

More articles from Ecology, The Environment and Conservation:

nachricht Preservation of floodplains is flood protection
27.09.2017 | Technische Universität München

nachricht Conservationists are sounding the alarm: parrots much more threatened than assumed
15.09.2017 | Justus-Liebig-Universität Gießen

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Salmonella as a tumour medication

HZI researchers developed a bacterial strain that can be used in cancer therapy

Salmonellae are dangerous pathogens that enter the body via contaminated food and can cause severe infections. But these bacteria are also known to target...

Im Focus: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

3rd Symposium on Driving Simulation

23.10.2017 | Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

 
Latest News

Single nanoparticle mapping paves the way for better nanotechnology

24.10.2017 | Physics and Astronomy

A quantum spin liquid

24.10.2017 | Physics and Astronomy

Antibiotic resistance: a strain of multidrug-resistant Escherichia coli is on the rise

24.10.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>