Okay, I really hate to be the downer here, because I totally get the reassurance found in having a monthly scan. But I also believe in making an informed decision, rather than emotional one. It is okay to just trust yourself and your baby that everything is okay. The FDA and the National Institutes of Health have both warned women to not have ultrasounds unless there is a medical indication to do so- as in you had bleeding or a car accident. If there are no signs of problems, they prefer you not get an ultrasound. The way I think about it that ultrasounds are like drinking alcohol in pregnancy- there are safe amounts and unsafe amounts, and exactly where that line is is not entirely known. So you have to decide for yourself where you feel comfortable. Just like a glass of wine a few times in pregnancy is fine, I'm sure a few ultrasounds in pregnancy are fine. But if you have too much alcohol in pregnancy, your baby can have FAS and if you have too many ultrasounds, it can effect the baby's brain and bone development. So anyway, if you want more info in terms of weighing the pros and cons here are some good websites.
http://www.mothering.com/articles/pr...und-risks.html - good article for covering the pros and cons
http://www.alternamoms.com/ultrasound.html- this one has a bunch of summaries of research at the end.
http://www.fda.gov/FDAC/features/2004/104_images.html- In the US, the FDA is against ultrasounds for non-medical reasons.
I would just read what you can on the topic and trust yourself to make a decision that is right for you and your baby. If that is a scan every month, then okay. And if it's to hold off on scans, that is okay too. It's your decision.