As tempting as it may be to have children super close together for some moms, researchers are now advising women of all ages to wait at least one year before getting pregnant after their last baby’s birth.

A new study, conducted earlier this year by researchers from the University of British Columbia and the Harvard TH Chan School of Public Health, oversaw the pregnancies of nearly 150,000 Canadian women and determined that regardless of age, multiple risks were increased for women who waited just six months to conceive again.

While certain age ranges didn’t see much change in certain risk factors between waiting six months to get pregnant again and 18 months, others did — for example, in women older than 35, researchers found a .62 percent risk for maternal mortality or severe morbidity at six months compared to 18 months (.26 percent).

The study — published in the journal JAMA Internal Medicine — concluded that for women aged 20 to 34, this particular risk was almost equal in either time frame: .23 percent at six months versus .25 percent at 18.

Want all the latest pregnancy and birth announcements, plus celebrity mom blogs? Click here to get those and more in the PEOPLE Parents newsletter.

RELATED: Moms of Infant Boys Are Over 70 Percent Likelier to Develop Postpartum Depression, Study Shows

However, “adverse fetal and infant outcome risks” were increased across the board for women who got pregnant six months after delivering their last child as opposed to later.

For women in the 20 to 34 bracket, that number jumped to 2 percent at six months as opposed to 1.4 percent at 18, while women 35 and older saw an increase from 1.8 to 2.1 percent.

Premature birth chances also increased for both groups, with women in the younger range having a 5.3 percent risk at six months of waiting versus 3.2 percent at 18 months. In women 35 and older, researchers found this risk jump (though not quite as much) as well, from 3.6 percent at 18 months to 5 percent at six.

According to the BBC, researchers found that the ideal time between giving birth and conceiving again was 12 to 18 months. Previously, the World Health Organization recommended at least 18 months between pregnancies, with 24 months being ideal, the BBC reports.

“The findings of this study suggest that short interpregnancy intervals are associated with increased risks for adverse pregnancy outcomes for women of all ages,” the study concluded.