7 reasons people shouldn't have children, according to science

If you're trying to decide if you should have kids, these studies could help. debasige/Shutterstock.com Whether or not you should become a parent is often a fraught decision.

With the US fertility rate at an all-time low, more people are rejecting the idea that you have to have children.

While it's ultimately your decision, there are several factors at play that potential future parents should consider.

If you're looking for a straightforward answer to the question of whether or not you should have a child, you'll be sorry to hear that it doesn't exist. Certainly, there are several reasons people shouldn't have children - your decision to become a parent could make your life utterly miserable and send your career careening into the abyss. But, then again, it could be the most fulfilling decision you've ever made and set you up to take on the world. Or it could fall somewhere in the middle. Simply put, it's complicated - and in many ways, too subjective - and I doubt we'll ever have a comprehensive, one-size-fits-all answer. The decision is, ultimately, up to you. But hopefully, these studies will begin to unpack the question of whether you should or shouldn't have children and help you better understand the factors at play.

Having a child contributes to global warming REUTERS/Andres Forza In the bioethics world, there has been some discussion of late regarding the morality of having children considering the effect on the environment. Writing for CNBC, Travis Rieder, the assistant director for education initiatives, director of the Master of Bioethics degree program, and research scholar at the Berman Institute of Bioethics, argues that having a child is a major contributor to climate change, and the logical takeaway is that everyone should consider having fewer children. Rieder cites research out of Oregon State University that found that having one fewer child would have a far greater effect on carbon dioxide emissions, and therefore be one of the best things things you could do for the environment, compared to reducing home energy use, travel, food choices, and other routine activities that result in carbon dioxide emissions.

Parents, especially mothers, face bias in the workplace Francisco Osorio/Flickr "Motherhood triggers assumptions that women are less competent and less committed to their careers," reads a recent report out of LeanIn.Org and McKinsey & Company. "As a result, they are held to higher standards and presented with fewer opportunities." The report points to a study out of Cornell that found employers tended to discriminate against mothers. As part of the study, researchers sent employers fake, almost identical résumés with one major difference: some résumés indicated that the job applicant was part of a parent-teacher association. While male job candidates whose résumés mentioned the parent-teacher association were called back more often than men whose résumés didn't, women who alluded to parenthood in this way were half as likely to get called back than women who didn't. The study participants also rated mothers as the least desirable job candidates and deemed them less competent and committed than women without children or men. At the same time, applicants who were fathers were rated significantly more committed to their job than non-fathers and were allowed to be late to work significantly more times than non-fathers.

You may earn less money if you're a mother REUTERS/Damir Sagolj "For most men the fact of fatherhood results in a wage bonus; for most women motherhood results in a wage penalty," research group Third Way's president Jonathan Cowan and resident scholar Dr. Elaine C. Kamarck write about "The Fatherhood Bonus and The Motherhood Penalty: Parenthood and the Gender Gap in Pay." In the academic paper, author Michelle J. Budig, a professor at the University of Massachusetts-Amherst, writes that, "While the gender pay gap has been decreasing, the pay gap related to parenthood is increasing." In her 15 years of research on the topic, Budig found that, on average, men earn 6% more when they have and live with a child, while women earn 4% less for every child they have. Sadly, "the women who least can afford it, pay the largest proportionate penalty for motherhood," as high-income men see the biggest pay raise for having children while low-income women see the biggest dip. "A lot of these effects really are very much due to a cultural bias against mothers," Correll tells The New York Times. The New York Times notes that in her previous work, Budig found that dads taking more parental leave mitigates the motherhood penalty, as evidenced by countries like Sweden that incentivize fathers to take paid leave and have a smaller pay gap.

Friendships inevitably change after the birth of a child, sometimes for the worse Flickr / Serge Melki Discussions of success often come down to career advancement and money, but other important factors like our interpersonal relationships play a vital role in our well-being. When Child magazine surveyed about 1,000 parents, almost half of the dads and moms surveyed said they had fewer friends after their children were born. And while 69% of women and 67% of men felt satisfied with their friendships before having kids, only 54% of women and 57% of men said they felt that way afterward. One factor at play could be time. Before they had kids, women spent 14 hours a week with friends, while men spent an average of 16 hours a week with friends. After kids, those numbers dropped to five hours with friends for women and six hours for men. Another factor is the inevitable shift in what people want to get out of their friendships. For example, almost all the women surveyed said they depended on their friends for having fun before they had kids - that number dropped to half once they had a family. A majority of the women surveyed said they felt that having friends who are good listeners became more significant after having kids.

Marriages tend to suffer after the birth of a child Shutterstock In a meta-analytic review of previous studies, researchers concluded that parenthood tends to have a negative effect on marital satisfaction because of the conflicts that arise from reorganizing roles in the marriage and the parents' restriction of freedom. The study also indicated that the more children there are in the family, the lower the parents' marital satisfaction. The difference in marital satisfaction was most pronounced among mothers of infants, while for men, the effect remained similar across ages of children. And parents in high socioeconomic groups, of younger ages, and who have given birth in more recent years tend to see the most negative effects on their marriage.

Parents tend to be less healthy than non-parents Joe Raedle/Getty Images John Dick, founder of CivicScience, a polling platform that catalogued more than 1 million responses to its "Parental Status" poll, writes on Quartz that non-parents tend to lead healthier lifestyles than parents. According to the poll results Dick shared, non-parents are 75% more likely than parents to report an average of more than eight hours of sleep each night, while parents are 29% more likely to report less than six hours of sleep per night. Unsurprisingly, parents are 28% more likely to say they drink coffee "every day without fail" than non-parents. Non-parents are also 73% more likely than parents to say they "never" eat at fast food restaurants and 38% more likely to exercise at a gym once a week or more; while parents are 17% more likely to say they never exercise, 10% more likely to consider themselves overweight, and 54% more likely to smoke cigarettes every day, Dick reveals.