Yep heard that one before, the dandruff would result in serious nakakahiya, hence thou shall't not copulate late in pregnancy (without a condom )
My mother was Irish and Catholic and had a similar range of insane superstitions, she was born in 1919 though, long time ago in UK cultural terms (I was a late baby).
So much of the Philippines reminds me of my own upbringing in a not terribly rich 3/4 Irish Catholic family in Scotland
Jim