According to the Ancient Chinese Gender Chart, if your wife is conceived in one of the following time periods in 2021, you have more chance to get a baby boy:
Jun 10 - Jul 09 (29 lunar years old, the 5th lunar month) Jul 10 - Aug 07 (29 lunar years old, the 6th lunar month) Aug 08 - Sep 06 (29 lunar years old, the 7th lunar month) Sep 07 - Oct 05 (29 lunar years old, the 8th lunar month) Oct 06 - Nov 04 (29 lunar years old, the 9th lunar month)
Jun 10 - Jul 09 (29 lunar years old, the 5th lunar month)
Jul 10 - Aug 07 (29 lunar years old, the 6th lunar month)
Aug 08 - Sep 06 (29 lunar years old, the 7th lunar month)
Sep 07 - Oct 05 (29 lunar years old, the 8th lunar month)
Oct 06 - Nov 04 (29 lunar years old, the 9th lunar month)