Pregnancy week 40

Filed under Third trimester · Pregnancy Week to Week editorial team

At almost 9 or 10 pounds and around 21 1/2 inches long, the baby is very snug in the little room it has within the uterus. Although due date predictions are carefully conducted, sometimes they are incorrect. For this reason, first time mothers especially usually deliver at week 41 or 42 instead of week 40. For everyone else, week 40 is the most probable time for delivery. Although labor should never be attempted to be induced before week 40, there are some natural methods that have been proven to work. Sex is a well-liked method of inducing labor and works because semen contains prostaglandins, which help encourage contractions and induce labor. Orgasms also help trigger labor. Walking is another technique that has been used for centuries. Walking helps the baby get itself down into the pelvis and regularize contractions. This can also aid in calming the pains due to contractions. Spicy foods are also a favorite method, and since the baby has moved down from the digestive system, can be a long awaited treat. Nipple stimulation is also a very well recognized method of inducing labor. However, this can cause extreme contractions which may be harmful to the baby. A doctor should be consulted before embarking on this method. Castor oil is another potentially dangerous method and is suggested for women who have gone past their due dates. It may cause diarrhea and other problems so a doctor should always be consulted first. Sometimes, the doctor will break the membranes connected to the amniotic fluid, which will push the body into labor. This is referred to as membrane stripping.

For second pregnancies and beyond, the head will engage just a few hours before labor. The body of the baby is mostly fat, 15% of it, at this point. The toe nails and fingernails will probably have to be trimmed by the time it is born and the genitals may be enlarged because of the presence of the mother’s hormones in the baby at the time of birth. This will all disappear within a few short days post delivery.

Current guidance (today's medical sources): Week forty is the estimated due date, though only a small share of babies arrive exactly on it — many come a little before or after. The baby is fully developed. If pregnancy continues past the due date, providers monitor more closely and may discuss options such as membrane sweeping or induction; these decisions are individual and made with a provider. Reduced movement should always be reported promptly.

Sources: NHS — 40 weeks pregnant; ACOG — When Pregnancy Goes Past Your Due Date; Mayo Clinic — Fetal development: The 3rd trimester. Informational only. See our sources & medical-review policy.

Informational only — not medical advice. Pregnancy Week to Week is a general educational reference. It is not a substitute for professional medical care, diagnosis, or treatment. Every pregnancy is different: always consult your doctor, midwife, or other qualified healthcare provider about your own pregnancy, and never disregard or delay professional advice because of something you read here. In an emergency, contact your maternity unit or local emergency number immediately.