(WLTX, AP) - Serena Williams is one of the most impressive athletes of our time. But here's another feat to add to her illustrious career: she apparently won a Grand Slam while pregnant.

Williams announced on social media Wednesday that she was expecting a child, and that she was 20 weeks along. Well, by that reasoning, when she played in--and won--the Australian Open in January, she would have been several weeks pregnant.

Now granted, she may not have known that at the time, and plenty of women their lives as normal, including engaging in intensive physical activity, before being aware of a pregnancy. But it's still interesting.

The 35-year-old Williams has not competed since then, however, citing a knee injury when withdrawing from tournaments at Indian Wells, California, and Key Biscayne, Florida.

Williams, who holds the record for most Grand Slam tennis titles in the open era, got engaged last December to Reddit co-founder Alexis Ohania.

This is the first child for both of them. The baby is due in the fall, according to a spokesperson for Williams.