Graeme McDowell has become the latest golfer to pull out of the Rio Olympics, following hot on the heels of Rory McIlroy's decision to miss the tournament in August.
The Irish former U.S. Open champion issued a statement saying his wife was due to give birth a couple of weeks after the Games.
McIlroy withdrew because of fears over the Zika virus which can cause birth defects.
"I woke yesterday morning to the news that Rory McIlroy had withdrawn from the Irish Olympic Golf team, putting me in line for an automatic spot on the team," McDowell said in a statement.
"As many within golf will know my wife Kristin is pregnant and is due to have our second child just a couple of weeks after the Olympic Golf competition concludes.
"I made the decision many months ago, before I was on the team, that I would not play or travel outside the U.S., where I and my family live, in the weeks running up to the birth."
However Padraig Harrington has stepped up for Ireland saying "it would be a huge honour for me to represent Ireland at the Olympic Games, having played an active role in golf's bid to be re-included in the Olympic Games programme," said Harrington, a three times major champion, in a statement.
McDowell's decision left Harrington as next in line, based on current ranking points.
"I will work very hard over the next few weeks to achieve this selection," he said in a statement issued by the Olympic Council of Ireland.
The Irish golf team will be announced next month, with Shane Lowry sure to be one of the players.
The International Golf Federation said it was disappointed but recognised the "unique circumstances" McDowell faced.
The two Northern Irishmen join a growing list of players deciding not to go to Brazil.
Fiji's Vijay Singh, Australia's Marc Leishman and South Africa's former Masters champion Charl Schwartzel have all pulled out of the Olympics due to concerns over Zika.
Australian world number eight Adam Scott and South Africa's world number 14 Louis Oosthuizen have also opted out for scheduling reasons.
U.S. health officials have concluded that Zika infections in pregnant women can cause microcephaly, a birth defect marked by small head size that can lead to severe developmental problems in babies.
The World Health Organization has said there is strong scientific consensus that Zika can also cause Guillain-Barre, a rare neurological syndrome that causes temporary paralysis in adults.