Regardless of how many times a woman is pregnant, some things never change. The uterus stretches each time, bringing with it a host of small discomforts. Increasing body weight and weight distribution stress a woman's back and joints, affecting her posture and often leading to back pain. There are, however, some notable differences between a first pregnancy and a fourth, most of which are simply factors of a woman becoming more physically and psychologically accustomed to the changes of pregnancy.
One of the most noticeable differences between a first-time mom and a woman who has had several babies is that first timers tend to show less and show later than more experienced moms. The reason for this is that the first time a woman becomes pregnant, her uterus and abdominal muscles are quite tight. As the uterus stretches, it moves out of the pelvis and into the abdomen, Heidi Murkoff and Sharon Mazel explain in their book, "What To Expect When You're Expecting." This begins to stretch the abdominals, which eventually loosen and allow the stomach to protrude. Typically, women start to show earlier with each subsequent pregnancy, meaning that a fourth-time mom might show as early as the ninth or 10th week of pregnancy.
Some of the symptoms of pregnancy are different for very experienced moms. For instance, because more experienced moms know what to look for, they tend to notice pregnancy earlier than women who are pregnant for the first time, according to Dr. Raymond Poliakin author of "What You Didn't Think to Ask Your Obstetrician." They're familiar with their symptoms and recognize them for what they are rather than mistaking them for an illness or an approaching period. Further, notes Poliakin, first-time moms may feel a baby move for several weeks before recognizing it as something other than gas. Fourth-time moms, being far more experienced in the sensations of pregnancy, recognize their babies' movements many weeks earlier; some may even note movement as early as the 17th or 18th week.
One of the major differences between a woman's first pregnancy and her fourth is her age during the pregnancy. Because a woman is at least four years older during her fourth pregnancy, her likelihood of twins is higher than it was during her first. In their book, "Hands Off My Belly," Dr. Shawn Tassone and Dr. Kathryn Landherr explain that a woman's likelihood of twins increases with age, because older ovaries are more likely to allow two or more eggs to mature. Further, older women have a higher risk of giving birth to babies with chromosomal abnormalities, making genetic testing increasingly advisable in a fourth pregnancy as compared with a first.
The type of delivery a woman experiences with her first pregnancy doesn't necessarily affect the way her subsequent deliveries will go, despite the common misconception to the contrary. Increasingly, women who have had C-sections with a first child go on to give birth vaginally, particularly with advancements in incision placement, note Drs. Tassone and Landherr. Further, each baby is different, and baby size and placement significantly affect the labor experience, meaning that a woman who had a very difficult labor the first time may be in for a much easier time later on, or vice versa. Typically, however, labors are shorter during each subsequent pregnancy, meaning that fourth pregnancy labors may be quite efficient.
In general, many women benefit from additional emotional security during pregnancies in which they are experienced mothers. Murkoff and Mazel note that the emotional stress of a first pregnancy can be quite severe and stems from a woman's sense of life change, fear of the unknown and nervousness about the pain of labor and delivery. Fourth-time moms know what pregnancy feels like, and they know what to expect during labor. They're comfortable with how to care for a newborn, and their methods of parenting are well established, giving them the ability to simply relax and enjoy the pregnancy.