The risk of miscarriage is also far lower: It's about 10 percent for women in their 20s, 12 percent for women in their early 30s, and 18 percent for women in their mid to late 30s. Miscarriage risk jumps to about 34 percent for women in their early 40s, and 53 percent by age 45. Pregnancy is often physically easier for women in their 20s because there's a lower risk of health complications like high blood pressure and diabetes.