<s>[INST] My wife is 4 months pregnant and has been having an itchy spine/back for a while, when she takes pre-natal supplements it is worse. We cant afford to see a doctor and get tests. What could be causing her back to itch? She says it could be that the baby has a blood type that she is allergic too, is this possible? [/INST] Greetings from Chat Doctor. Thanks for posting your query.  No that is not the cause of Itchy back. Most likely it is due to an allergy to one of her pre natal supplements.  I advise you stop one of the supplements for a week and observe, if there is a relief from itching then ask your doctor for an alternative for that supplement. If there is no relief then restart that supplement and stop the other supplement and observe.  Till then, she can apply a cream called Renovate over her back. Ask your doctor for the prescription. Hope this information is useful to you. Any clarification feel free to ask. </s>