Kate Hudson has been praised as a ''really good mom'' by her best friend Erin Foster.

The 38-year-old actress - who has Ryder Russell, 14, and Bingham Hawn, six, from two previous relationships - is currently expecting her third child, a girl, with her boyfriend Danny Fujikawa, and her best friend Erin, who is Danny's stepsister, can't wait to see Kate become a mother again.

Erin revealed: ''Kate is a really good mom. She's strict. She's really good with boundaries. She's tough. And Danny is like a hippie. He's very ethereal and go-with-the-flow, so it will be interesting to see how that happens.''

The 'Bride Wars' star announced her pregnancy - which is the first for her and Danny together - in a gender reveal video on Instagram in which she and Danny, along with her two sons, popped black balloons which were filled with pink confetti, signalling a baby girl.

Speaking about the video, Erin said: ''[Kate] wanted a girl so badly and they really didn't know until they popped the balloons and pink came out, so it was really exciting. I don't know if you saw Sara [Foster, Erin's sister] jumping on top of Kate like a psychopath but we were just so excited about her having a girl.''

Erin also shared the sweet story of how Kate and Danny fell in love, which occurred 15 years after they first met when Danny joined Erin's family.

Speaking to People magazine, Erin said: ''It's a really beautiful connection because ... our parents got together when [Danny] was like 15 years old, so Kate has been [a] part of our family. She [was] having dinner with us, and they're there, and then all of a sudden they looked at each other differently after 15 years, and suddenly they fell in love, and it was this crazy thing to witness.

''She kept going, 'Well, wait a second. Me and Danny can't be a thing. It's not a thing, right?' And we're like, 'It looks like it's a thing!' And now they're having a baby. It's just really amazing.

''When I say timing is everything, it's so true, because you're around someone for so long and you're both not ready to be in that long-term relationship, and you're young, and you go through other relationships and you don't think of each other that way.

''And then one day you look at each other differently and you don't have to put on any airs or pretend to be somebody else or try to be cool because you already know each other.They just found each other at a really beautiful time in their life and it just happened so seamlessly.''