Kate Middleton and Prince William
Kate Middleton has reportedly used her maternity to get back in shape, according to a report. In this photo, dated Sept. 18, 2015, Middleton and Prince William attend the opening ceremony ahead of the 2015 Rugby World Cup at Twickenham Stadium, Sept.18, 2015, in London, United Kingdom. Getty Images/David Rogers

Kate Middleton returned to her royal duties last week, after four months of maternity leave, looking fit and fine. The Duchess of Cambridge also utilized her leave to get back in shape after giving birth to second baby Princess Charlotte, according to a report in OK! Magazine’s latest issue.

"Kate looked thinner than ever. It's clear that she spent the summer just looking after her kids. William tries to help as much as he can, but at the end of the day Kate is the one who gets up to feed Charlotte and rock her back to sleep; there are no night nurses. She did the same thing when George was born," a source told the magazine, according to Classicalite.

Meanwhile, the 33-year-old mother of two is not going to dress Charlotte up in dresses for at least a year, Middleton's favorite children’s designer, Rachel Riley said, People reported Tuesday.

"Because they're a traditional family, I'm sure that she'll wear baby suits for the first year, and then only when she's walking will she then move into dresses. Even in terms of separates, I don't think she'll be wearing separates until much later," Riley added.