Jason Day, the world’s No. 1-ranked golfer, on Tuesday became the latest professional to decline a bid to the Rio Olympics over fears of the Zika virus, according to the Associated Press.

“Day says his only reason for not going is concern over transmission of the mosquito-borne virus that has been linked to severe birth defects. The 28-year-old Australian says while the risk is slight, it’s not one he is willing to take because he plans to have more children,” the AP reported.

Day is the defending PGA champion and has finished in the top 10 in each of the last five majors.

Last week, fourth-ranked Rory McIlroy also announced his decision not to play in the Olympics, which is hosting a golf tournament for the first time in 112 years. He also cited fears of the Zika virus, saying he did not want to endanger his fiancee, with whom he plans to start a family. Women who are pregnant or hope to become pregnant have been advised not to travel to Rio for the Olympics because of Zika, which is mainly borne by mosquitos and has been shown to cause birth defects. It also can be transmitted sexually.

Shane Lowry, the world’s 25th-ranked golfer, also announced Tuesday that he would not be competing for Ireland in Rio because of Zika.

“Based on a number of consultations with leading medical experts in recent days, I feel that I would be putting my family’s health at risk by being in Brazil at the current time,” Lowry said in a statement.

Lowry, who led this year’s U.S. Open entering the final round before tying for second, got married this year and said he and his wife hope to start a family soon.

“Based on these circumstances, I have received firm medical advice that I should not travel to Rio this summer,” he said.