Johan Askling, MD, a lead investigator in a study conducted in Sweden on the correlation between morning sickness and a baby's gender told Web MD, «We believe that there is something causing morning sickness that is more common among female pregnancies,
like human chorionic gonadotropin.»
At the end of this week, your body begins to produce small amounts of the pregnancy hormone
human chorionic gonadotropin (hCG), which can sometimes (but not always) lead to early pregnancy symptoms
like tender, swollen breasts and fatigue.