I don't have any. But back in the day, it wasn't particularly proper for ladies to be photographed while with child. At least, the belly wasn't shown-off like many celebrities do today. Princess Grace used her namesake Kelly bag to shield photographers' view of her belly.
Real princesses always wear sleeves so why do we all go for strapless?
I think there have to be some photos (whether we can find them now is another issue, of course). It wasn't necessarily proper to show off one's pregnancy the way it is today, but there were plenty of royal women in the 60s who were photographed during various engagements when they were quite noticeably pregnant. I know I've seen both Margrethe, Anne-Marie, and Sonja.