Britain's Catherine, the Duchess of Cambridge
Britain's Catherine, the Duchess of Cambridge is given two teddy bears by patient Ava Watt as she arrives to visit Great Ormond Street Hospital to officially open the Mittal Children's Medical Centre, in London, January 17, 2018. Reuters/Frank Augstein/Pool

Kate Middleton went on a solo outing to a children’s hospital on Wednesday without her husband, Prince William, and without her engagement ring. There’s a practical reason for that, though.

The pregnant Duchess of Cambridge visited young patients at Great Ormond Street Hospital and helped open the new Mittal Children’s Medical Centre in a bright red coat on an official outing. The duke did not accompany her this time as this was a solo trip. Also noticeably missing was her stunning sparkler.

Kate was only wearing her simple gold wedding band but not her huge sapphire and diamond engagement ring while talking with the patients. According to People, Kate left the ring behind because the hospital has a policy on wearing minimal jewellery. The duchess would have to wash her hands thoroughly before entering the treatment areas and wards, and so it was necessary for her to remove her jewellery before entering.

It was one of the rare times when Kate had to leave her engagement ring behind. She has been wearing the stunning 12-carat oval blue Ceylon sapphire and 14 solitaire diamonds ring since becoming engaged to William in 2010. She also wore it while visiting Coventry University’s new Science and Health Building with William on Tuesday. The ring first belonged to the late Diana, Princess of Wales, who was William’s mother.

Kate did put the ring back on after her morning hospital visit. She was seen wearing it again at the Wimbledon Junior Tennis Initiative on the same day. The initiative promotes the benefits of playing tennis, introducing local children to the sport through free tennis coaching lessons.

The duke and duchess, who are already parents to 4-year-old Prince George and 2-year-old Princess Charlotte, are expecting their third child in April.

Britain's Catherine, the Duchess of Cambridge, visits Bond Primary School in Mitcham to see the work of the Wimbledon Junior Tennis Initiative, in London, January 17, 2018.
Britain's Catherine, the Duchess of Cambridge, visits Bond Primary School in Mitcham to see the work of the Wimbledon Junior Tennis Initiative, in London, January 17, 2018. Reuters/Arthur Edwards/Pool