for second time mums: any difference in morning sickness with your two pregnancies?

1st: Never vomitted, occasional nausea at random time of the day. 2nd: Nausea the whole day, occasional vomitting. Still having nausea at 18 wks now and constant burping even when I did not eat. Not sure if baby gender has any effect on the nausea. First born is a boy and 2nd gonna be a girl.