Regarding the baths thing - I understand that your temp needs to not be sustained at above basal temp for ten minutes or more. This is why hot tubs are forbidden.
In reality, a bath is unlikely to maintain a very high heat - they start getting cooler as soon as you've finished running them.
You can measure the temp with a thermometer if you want to be very careful but generally, just checking that it's not uncomfortably hot against your skin will be enough. Also, the main issue is with the neural tube development. Neural tube closes at around 10 weeks, at which point, it becomes safer to indulge in warm baths.