Pippa Middleton is taking tips from Serena Williams' pregnancy.

The 34-year-old socialite - who is expecting her first child with her husband James Matthews - is keen to keep up her exercise whilst she is expecting, similarly to how the tennis star did before she welcomed Alexis Olympia Jr. nine months ago.

Writing in her column for Waitrose Kitchen, she shared: ''I've been a tennis fan since childhood, as a player and spectator, and have been keen to continue playing safely throughout my pregnancy. Take Serena Williams. She famously proved that women can play a high level of tennis from two months (when she won the 2017 Australian Open) up to eight months. Few of us can relate to this elite excellence, but if you're a healthy, well-trained player with an uncomplicated pregnancy there's no reason why you can't continue a good level of tennis.

''I'll [have to adjust to] a four to five-day-a-week [fitness] routine. [I've been told to] keep two feet on the ground when hitting strokes and to avoid sharp turns and quick movements, particularly as I approach the due date.''

Meanwhile, Pippa - who is the younger sister of the Duchess of Cambridge - previously expressed the importance of continuing with exercise and sport throughout her pregnancy.

She shared: ''I've noticed my body change and weight increase, but through effective exercise and sports I feel that it's been strengthened to support a healthy pregnancy, birth and recovery. And ensure that post-baby, my old favorite jeans will still fit eventually!''