Some women may experience an increase in the number of colds during their first pregnancy, which is related to the adjustment of the body’s immunity. After pregnancy, the fertilized egg, as a foreign substance, has to be laid in the uterus, and for the body’s immune system, immune rejection occurs, which is not conducive to the bed and growth of the uterus. In order for the fertilized egg to better implant and grow in the uterus, the body’s immune system undergoes a series of adjustments and a decline in immune rejection occurs, with the consequent down-regulation of immune function. This period may be characterized by an increase in the number of colds than usual during the first pregnancy when exposed to external pathogenic agents, such as cold and flu viruses. Therefore, during pregnancy, it is important to take rest and maintain good living and eating habits to improve your ability to fight colds.