Update:
Had a very positive conversation with HoS, and they are happy to support me with whatever I decide is best. They were more than reasonable and very sympathetic.
Phew!
Thanks everyone for your valuable input.

Thanks for the input everyone. The benefits are no problem because of husband working full-time for the same school, but the visa might be a different story. I get on well with line manager and HoS so I might see if can have an exploratory chat. They are not legally obliged to offer me anything, so I would very much have to rely on goodwill I hopefully have built up with the school. I certainly don't intend to make any demands or set ultimatums. If anyone else has any wisdom or experience to share, I'll keep checking this thread. Thanks again to the community.

I'm about to renew my contract with a British International School in South East Asia. I'm pregnant and due to give birth before summer break. Both my husband and I work full-time at the same school, working very long days (7am-4pm but often later). Now that I'm expecting my second child, I can't imagine being away from my newborn baby this much. I therefore thought of asking SLT if I can possibly work an 80% contract next academic year (taking a 20% pay cut). Giving me a full day off, or two half days. This is my third international school in Asia, and I've never met an international teacher who worked anything less than full-time. This is why I'm trepidatious about asking SLT. Does anyone have experience negotiating reduced hours or working part-time? Especially after maternity leave? Would be very grateful to hear your experiences.