The prevalence of mother-to-child HIV transmission in Botswana has dropped to four percent, marking the first time that a developing nation with a high HIV infection rate has lowered its transmission level close to levels in the United States and Europe. In the U.S., the number of positive babies born of mothers who have the virus is less than two percent.

Thirty-four percent of pregnant women in Botswana are HIV positive, reports the Boston Globe. Experts say the encouraging rates can in part be attributed to the fact that all pregnant women in the country are tested for the virus unless they opt out.