Foreign trips can easily go wrong for world leaders, and what to wear is something that is often heavily scrutinised.

Religion and clothing go hand in hand when foreign leaders visit other nations, and they have created some of the headlines for Donald Trump's first trip as US president.

In recent years, women from Michelle Obama to Theresa May have all chosen to forgo wearing a headscarf or veil while in Saudi Arabia where there are strict laws on what women can wear.

Melania Trump followed in their steps by dressing conservatively but without a veil.

Today (24 May), the Trump's visited the Vatican to meet with Pope Francis where there are similarly tight rules on what women should wear.

Melania and Ivanka Trump both wore black dresses and veils, traditional Vatican attire for women considered respectful, though not mandatory.

Women are expected to wear black with a veil. White dresses, in the past, have been permitted only for a handful of Queens and Princesses from Catholic regions.

The rules have in recent years been relaxed, with Camilla the Duchess of Cornwall opting for a pale gold dress without a veil.

Melania Ivanka Trump Pope
Pope Francis meets Melania and Ivanka Trump during a private audience at the Vatican Alessandra Tarantino/AFP

It appears that the Trump's chose to stick to the historic rules. Melania Trump is reportedly a Roman Catholic, while Ivanka has converted to Judaism.