A new United States study is nothing less than a warning for those women who lift heavy loads or work more than 8 hours a day. According to the study, women who work for over 40 hours per week or lift heavy loads could take longer time to get pregnant than women who do not work very hard.

In the study, researchers included about 1,739 nurses. All the nurses were trying to get pregnant during the time of the study. The study found that about 16% of them did not achieve their target to get pregnant within one year, while 5% did not conceive even after 24 months.

The study found that women who worked over 40 hours a week took about 20% longer time to conceive than women who worked 21 to 40 hours a week. Lifting heavy loads or shifting them also found tied to delay pregnancy. Lifting or moving about 25-pound loads many times a day has been found to delay pregnancy time about 50%.

Audrey Gaskins, a researcher at Harvard T.H. Chan School of Public Health in Boston and lead author of the study, said, “Our results show that heavy work, both in terms of physical strain and long hours, appears to have a detrimental impact on female nurses’ ability to get pregnant”.

During the new study, the researchers analyzed data of women who participated in a nationwide survey of nurses between 2010 and 2014. About 50% women in the study were at least 33 years old. More than 30% women in the study said that they work for more than eight hours a day, while 40% reported that they lift heavy loads.