Raphael’s La Donna Gravida (The Pregnant Woman) was painted between 1505 and 1506.
The woman in the portrait is wearing a very period-typical gown covered by a white apron. The bodices of early Renaissance era gowns were often laced together at the seams. When a woman was pregnant the laces could be loosened to provide extra room, but resulted in unsightly gaps between seams as seen in the previous painting I posted. Aprons were so commonly used to cover lacing gaps during pregnancy that they remained closely associated with maternity fashion well into the 18th century.