First babies are less likely to be “on time” at 39 weeks, and more likely to be a little late, between 41 and 43 weeks. Among full-term pregnancies, first babies are born about 1.3 days later on average.
The researchers found that 50% of all women giving birth for the first time gave birth by 40 weeks and 5 days, while 75% gave birth by 41 weeks and 2 days.
Warning Signs of Premature Labor
Menstrual-like cramps felt in the lower abdomen that may come and go or be constant. Low dull backache felt below the waistline that may come and go or be constant. Pelvic pressure that feels like your baby is pushing down. This pressure comes and goes.
About 5% of babies are born on their due date. In one study… 81% having their first baby went past the due date. 61% of second, third or later pregnancies went past the due date.
Premature birth is when your baby is born early, before 37 weeks of pregnancy. Your baby needs about 40 weeks in the womb to grow and develop before birth. Babies born before 37 weeks of pregnancy are called premature. Premature babies can have serious health problems at birth and later in life.
And another study of about 119,000 women in Northern California found that those who were on their first pregnancies or who were obese were more likely to deliver at 40 weeks or beyond, while those with complications like high blood pressure or diabetes were more likely to deliver before their due dates.
Rabin said there is no known biological reason why firstborn babies would be more likely to be early or late. After 42 weeks of pregnancy, a baby is considered overdue, Rabin said, and doctors become concerned about complications, such as an aging placenta that is not able to deliver proper nutrition to the baby.
First babies are less likely to be “on time” at 39 weeks, and more likely to be a little late, between 41 and 43 weeks. Among full-term pregnancies, first babies are born about 1.3 days later on average.
First-born babies are less likely to arrive on time – they're either too early or too late, studies have found. A normal pregnancy lasts about 40 weeks, according to the American College of Obstetricians and Gynecologists.
Only 7.6 percent percent of male babies and 5.5 percent of female babies were in the womb 42 weeks or longer. Males were also 1.5 times more likely to be born at 43 weeks or longer. The researchers noted that the most common reason for prolonged pregnancies is an error in calculating the due date.
Labor may be induced by: Inserting vaginal suppositories that contain prostaglandin to stimulate contractions. Giving an intravenous (IV) infusion of oxytocin (a hormone produced by the pituitary gland that stimulates contractions) or a similar drug. Artificially rupturing the amniotic sac.
Boys are more likely to be born before their due date. After the 40-week mark, however, the odds slightly favor a girl.
You at 40 weeks
Pregnancy normally lasts about 40 weeks – that's around 280 days from the first day of your last period. Labour usually starts a week either side of this date, but you might go overdue. Your doctor may suggest inducing labour – it's your choice whether to have this or not.
More than 90% are born two weeks either side of the predicted date. But, as noted above, only 4% (or 4.4%, ignoring pregnancies with complications etc) are born on the predicted date itself - in other words, the chance of this happening is less than one in 20.
About 60 out of 100 women give birth on or before their given due date. In another 35 out of 100 women, contractions start on their own within two weeks of the due date. But it takes longer in about 5 out of 100 women.
First babies are more likely to be late than second or third babies, but he also found firstborns are more likely to be born early compared with their younger siblings. He also found out on average, a first baby is born later than subsequent babies but not by much time; just by 16 hours.
Research suggests that about half of people giving birth for the first time give birth by 40 weeks and 5 days. 3 This finding suggests that when left alone to go into labor without intervention, first-time pregnancies often last longer than the 40-week estimate used when calculating due dates.
Induced labour is usually more painful than labour that starts on its own, and you may want to ask for an epidural. Your pain relief options during labour are not restricted by being induced. You should have access to all the pain relief options usually available in the maternity unit.
For first-time moms, it can last from 12 to 19 hours. It may be shorter (about 14 hours) for moms who've already had children. It's when contractions become strong and regular enough to cause your cervix to dilate (open) and thin out (efface).
Spending most of your time in bed, especially lying on your back, or sitting up at a small angle, interferes with labor progress: Gravity works against you, and the baby might be more likely to settle into a posterior position. Pain might increase, especially back pain.
High physical demands, like those listed above, may increase risks for adverse birth outcomes. Prolonged standing or heavy lifting can cause an increased chance of miscarriage or preterm delivery (premature birth).
You may feel some cramping and pain in your lower back and groin as labor nears, especially if this isn't your first pregnancy. Your muscles and joints are stretching and shifting in preparation for birth.
A normal cycle can be between 21 to 35 days, and some people can even have cycles that range outside of that. Regularity isn't that common, so there's a fair chance that the calculation will be off, but the last menstrual period measurement is still used because it's considered fairly reliable most of the time.