Hi, I'm so sorry you're going through this. I totally understand wanting to do right by your baby, many of us who are superstitious feel the same way. From what I hear, there are quite a few options around Singapore: some temples do rituals specifically for unborn babies at around $88 for a one-day session, and I've also heard of people getting small blessing items (like sets of 30) for about $15 as part of home prayers. A friend mentioned that the Buddhist youth groups sometimes have longer rituals during the seventh lunar month that span about a month and are quite affordable too, which gave her peace of mind. I'd suggest asking your temple directly, they often know local practitioners and can guide you on what feels right for your family's beliefs, and costs can vary quite a bit depending on what you want to do. Sending you lots of care during this time.
You can go to 居士林 at Kim yam road. For tablet and prayer if never remember wrongly it’s about $35.