A midwife I worked with had 4 also with her 4th been twins. With her 3rd and 4th pregnancy she was told on ultrasound her scar was very thin. When she found out she was having twins she was really worried about her scar but she carried her twins to over 37weeks and they had a combined weight of over 7kilos. She didnt have any problems with any of her c/s or recoveries.