Robin Thicke's Girlfriend April Love Geary Pregnant with Girl

(TMZ) -- Robin Thicke is about to be a father again, with a girlfriend who is barely able to legally drink.

22-year-old April Love Geary is three months pregnant with a girl ... the baby is due March 1.

40-year-old Robin has been dating April for three years ... shortly after his wife, Paula Patton, filed for divorce.

Robin and Paula are still not divorced, and they have had an on-and-off custody war over their 7-year-old son, Julian. By the way, TMZ was told Robin and April told Julian this week and he's "super excited for a little sister."

March 1 would have been Alan Thicke's 70th birthday.

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