Waistlines rose considerably for a brief period in the late 1610s and early 1620s. This high waistline, along with the fashionable edition of lace aprons, created a rather accommodating style for pregnant women.
Marcus Gheeraerts II’s portrait of an unknown woman (top), often referred to as Portrait of a Woman in Red, was painted in 1620.
Interestingly, there is a great deal scholarly debate about whether the woman in this portrait and other contemporaneous “pregnancy portraits” are actually pregnant, or simply following fashion trends that make them appear so. Take for example Gheeraerts’ 1621 portrait of an unmarried, and presumably un-pregnant Susanna Temple (bottom).
I personally believe the Woman in Red is actually pregnant (note her hand resting on her stomach).