"Congrats to Jessica Simpson! Does this mean I now have the biggest baby bump in Hollywood?" Hannigan wrote after news broke Tuesday that Simpson, 31, gave birth to Maxwell Drew Johnson, a baby girl weighing a healthy 9 lbs., 13 oz.
Hannigan and husband of eight years Alexis Denisof are already parents to daughter Satyana, 3. The second-time mom-to-be is due in June, but recently joked on the Rachael Ray Show that folks seem to assume she's due earlier than that given the size of her bump.
"The last couple of times I've been at stores, people have been like, 'Oh you're ready to pop, right?'" she said in early April. "I'm like, 'Actually I have a couple more months.' Somebody said, 'You're sure there's not two?' I keep asking my doctor the same thing."