Once again, it seems Princess Mary is radiant with a telltale glow. It’s a glow the Danish media knows all too well, because they’ve seen it on Mary before – the past three times she was pregnant. And combined with what looks suspiciously like a small baby bump, it’s enough to whip the royal press into a frenzy of speculation that she and Prince Frederik are expecting their fifth child.

Under a glaring headline "Mary and Frederik on their wedding anniversary: Ready for number 5", Danish magazine Her&Nu described the extra special bond between the couple on their recent official visit to Korea. "Frederik often put his arm around Mary’s waist in a protective manner," it reported. "It was almost as if she needed extra care right now. They sent each other tender glances that made one think that perhaps they share a sweet secret that cannot yet be revealed to the public."

The baby speculation has come as a surprise to many – especially so soon after the birth of twins Josephine and Vincent in January last year, sister and brother to Christian, 6, and Isabella, 5. "Most 40-year-old mothers of four wouldn’t be ready for another pregnancy, but Mary and Frederik have space in their hearts for more children," reports the magazine. "They love being parents and it wouldn’t be surprising if they had a fifth child."

It's no secret that Mary and Frederik have always talked about being parents to a "big family", and baby number five would certainly fit in with that plan. "We feel very blessed with our four healthy, happy and lovely children," Mary said recently, though she added that it wasn’t all a barrel of laughs.

Are Princess Mary's wardrobe choices more proof she is expecting? Take a look in this week's Woman’s Day on sale Monday June 18, 2012.