Forced to leave work during pregnancy.

Last day my friend shared me her experience as an expected mom. She's working as an Engineer and with a good pay. Last month she informed her employer that she was pregnant. Soon after they asked her to sign a new contract with 50% pay. They said she must continue with this if she likes to work. Then they told her that she must resign from her work before delivery and can rejoin back after her delivery if she wants to work there. It shocked me given the fact that she has been working in that job for past 4 years as a permanent staff. #advicepls Is this normal in Singapore construction industry?