Sitting just one game back of the Atlanta Braves in the NL Wild Card race, the New York Mets will be without one of their best offensive weapons.

On Monday, the Mets placed designated hitter J.D. Martinez on the paternity list and recalled outfielder DJ Stewart from Triple-A Syracuse. Martinez will spend up to three days away from the team as he and girlfriend Brooke Wheeler are expecting the birth of their first child

The announcement comes as the Mets prepare for a six-game home stand, with the first series coming against Martinez’s former team in the Boston Red Sox.

Martinez, who signed a one-year, $12 million deal with the Mets at the eleventh hour of spring training, has been swinging a hot bat lately, slashing .308/.379/.577 with two home runs over his past seven games. Although he dealt with a back issue and struggled to start the year after his late signing, Martinez has been a key contributor in the middle of the Mets’ lineup. Overall, the veteran has posted a .777 OPS, belted 16 home runs and driven in 65 RBI in 105 games this season.

To fill in for Martinez, the Mets recalled Stewart from Triple-A. Stewart was demoted to Syracuse when the Mets added Jesse Winker at the trade deadline in late July. Since returning to the minors, Stewart boasts a solid .879 OPS over the past 22 games with a pair of home runs and four stolen bases.

The Mets will need all the help they can get this week if they want to continue to make up ground on the Braves. And it doesn’t help that Atlanta has two winnable series at home against the Rockies and the Blue Jays.

Martinez can be back as early as Tuesday as the MLB paternity list is available to players for one to three games.