Not your first pregnancy at 40

Im due 2nd of January with my 4th child and will turn 40 a month prior. I was so young when i had my first 3, 18- 20 and 25 and had 0 issues with the pregnancies and no pain relief with the deliverys which were all relatively quick, last 1 being an hour and half. I feel so worried this time around thinking about having the aminocentesis due to my age which i didnt have the first 3 times and the large age gaps.Constant thoughts of like can my body really do this, will i have a positive outcome. Does any1 have any positive subsequent pregnancy stories after age 39.