Abortion rates in developed countries are at a historic low, according to a new report, mostly due to increased use of contraception. However, the rates of abortion have remained unchanged in developing countries, where the practice is often unsafe.

The analysis of abortion data—compiled by the Guttmacher Institute and the World Health Organization and published in The Lancet on Wednesday—shows the annual abortion rate per 1000 women aged 15 to 44 dropped from 46 to 27 between 1990 and 2014 in developed countries. In developing countries, that rate fell only from 39 to 37.

“In developed countries, the continued fall in abortion rates is largely due to increased use of modern contraception that has given women greater control over the timing and number of children they want,” Gilda Sedgh, the lead author at the Gutmacher Institute, said in a statement. She said the abortion data highlight the need for increased access to modern contraception and family planning services in developing countries.

Read More: Women Now Have As Many Miscarriages As Abortions

The stark contrast between wealthier and poorer countries is also evident in the proportion of pregnancies that end in abortion. In developing countries, that percentage has declined from 39% between 1990 and 1994 to 28% between 2010 and 2014. In developing countries, that proportion increased from 21% to 32% of pregnancies during the same time periods.

The stability of abortion rates in the developing world raises safety concerns, according to the report.

“Estimates of the proportion of abortions that are unsafe are under development but we already know nearly 300 million dollars are spent each year on treating the complications from unsafe abortions,” said co-author Bela Ganatra. “The high rates of abortion seen in our study also provide further evidence of the need to improve and expand access to effective contraceptive services. Investing in modern contraceptive methods would be far less costly to women and society than having unwanted pregnancies and unsafe abortions.”

The analysis also found that the frequency of abortion appears to be roughly the same in countries with restrictive abortion laws as it is in countries where the practice is legal. The abortion rate in countries where abortion is illegal or allowed only to save a woman’s life is 37 abortions per 1000 women, while the rate in countries where the practice is legal is 34 abortions per 1000 women.

Get our Health Newsletter. Sign up to receive the latest health and science news, plus answers to wellness questions and expert tips. Please enter a valid email address. Sign Up Now Check the box if you do not wish to receive promotional offers via email from TIME. You can unsubscribe at any time. By signing up you are agreeing to our Terms of Use and Privacy Policy . This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply. Thank you! For your security, we've sent a confirmation email to the address you entered. Click the link to confirm your subscription and begin receiving our newsletters. If you don't get the confirmation within 10 minutes, please check your spam folder.

Write to Katie Reilly at Katie.Reilly@time.com.