Cramping at 19 weeks

Kayla • I`m 27. been with my husband for almost 12 years. we got married in October 2015. been trying for over 2 years. seen a Fertility specialist and was told I don`t ovulate on my own and my husbands sperm
when is cramping during early pregnancy serious? I've been having mild cramps all day today. they aren't terrible just uncomfortable. I was thinking it might be because my Jeans were too tight today. should I call the advise nurse?