The research, led by Paul Cohen-Bacri, Unilabs laboratories group, included 1940 men from a dozen countries. The team looked at parameters such as pH, the mobility of the gametes, concentration or morphology.

In overweight men (BMI between 25 and 30) or obese (over 30), sperm concentration in semen was 10 and 20 percent lower compared to the standard parameters. For those who accumulated more kilos, the mobility of the gametes was also reduced.

As for total sperm count, while people who are normal weight is around 184 to 194,000,000 per milliliter in men is overweight and obese 164/186 135/157 million.

Moreover, the drugs used in fertilization 'in vitro' for older women may increase their risk of having a baby with Down syndrome, according to a study by the London Bridge Fertility, Gynaecology and Genetics Centre (UK).

When the authors of this paper and studied these fertilized eggs, they saw that some had genetic errors. Such failure could cause the pregnancy to fail or cause the baby to be born with a genetic disease.

A detailed analysis of 100 of the defective eggs revealed that many of the errors were related to a duplication of genetic material in a spiral, known as chromosomes. Often, the errors generated an extra copy of chromosome 21, a circumstance that creates the appearance of Down syndrome.

Another study invites women who may become pregnant should brush their teeth properly and floss regularly to prevent gingivitis, a gum disease that affects the chances of conception. Specifically, periodontal disease may delay the time it takes to conceive a child an average of two months.

According to investigators, the culprit of this fact corresponds to the inflammation caused by oral bacteria that can have a ripple effect on the tissue in the reproductive system. This is the first time this disease has been identified among the factors that influence the likelihood of conceiving a child.