Your wife should have her blood pressure checked to be sure that it is not elevated. High blood pressure can give rise to nosebleeds. It is unlikely that your wife’s blood pressure is elevated at this stage of the pregnancy since such problems tend to be associated with the final months of pregnancy. However, it might be prudent to have it measured to be sure that it is normal. The nosebleed and headache would not have any adverse effects on the foetus unless they were due to an ongoing medical condition. Also, a solitary nosebleed would not have any effect on the foetus unless the level of blood loss was severe. The mother could become anaemic because of the blood loss but the foetus is well protected because the physiology of pregnancy is such that the foetus has first demand on the iron that is available.