January Jones almost went into labour at a New Kids on the Block concert.

January Jones

January Jones

The 37-year-old actress is a massive fan of the 90s boy band, but had to sit down for every other song when she went to see them perform when she was seven months pregnant, as she started having contractions prompting her sister to tell her to calm down.

In an interview on 'Conan', January revealed: "I have been a big fan (of New Kids on the Block) for a long time. They've been touring a lot in the last, like, five years, so I try to see them as much as I can. We met them backstage and I was escorted by security backstage - I think they thought we were getting escorted out, cause we looked a little ... crazy! But we met them and said 'hi'. Then during the concert I was jumping around and screaming, and then I started having contractions. So my sister said, 'If you have a baby at a New Kids on the Block concert, I will kill you!' So I had to sit down every other song."

The 'Mad Men' star went on to confess she'd bumped into NKOTB member Joey Macintyre in a restaurant recently, and "totally geeked out".

She told host Conan O'Brien, January said: "It was pretty cool. I totally geeked out. We were both waiting to get into this restaurant, we'd both gotten there early. We chatted for a long time. He had a wife-beater on ... he's pretty ripped."

Watch January Jones's interview on 'Conan' at 1am Tuesday 5 May on truTV (freeview channel 68).