But because due dates are often miscalculated, especially by ultrasound, doctors were frequently delivering premature babies who wound up spending time in the NICU. One study, for example, found that babies born by C-section before 39 weeks have more breathing difficulties than babies delivered by C-section after 39 weeks.
Furthermore, babies delivered electively at 37 weeks are four times more likely to end up in the neonatal intensive care unit or have serious respiratory troubles than babies born at 39 weeks or later; babies who arrive at 38 weeks are twice as likely to have complications.
Additionally, many of the inductions were unsuccessful because mom's body was not ready to go into labor. These women wound up with C-sections they most likely wouldn't have needed if they'd waited for labor to start on its own. You may be tempted to ask your doctor for an early induction because of swollen ankles or an aching back, but that final month is critical to your baby's good health. For starters, a compound in her lungs called surfactant, which enables her to breathe independently, continues to be produced in greater amounts during the last month of pregnancy and decreases her risk of developing breathing problems once she arrives.
Her liver is still undergoing changes that will enable it to properly filter toxins, such as jaundice -causing bilirubin, out of her body. Her skin is thickening and she is accumulating more body fat, which will help her to maintain her own body temperature after she's born. Brain development is still underway; at 35 weeks, for example, its volume is only about two thirds of what you'd expect at 39 to 40 weeks, says Dr.
Additionally, important brain and nerve connections are being made to help her suck, swallow, breathe, regulate her body temperature, and even sleep better once she's born.
Slowly but surely the birth culture of "induction or C-section on demand" has changed. Now, most doctors have received the memo that unnecessary inductions are potentially dangerous for moms and babies. If there are solid, compelling medical reasons to induce or schedule a C-section, then, by all means, that's what those procedures are there for.
However, if the medical reason can wait until a baby is full term, mothers and babies both fare better. Another great thing about these guidelines is that it spells out that a woman isn't really "over due" when she goes past her due date a week or two.
For a long time now, doctors have been fixed on that week mark as if a timer will go off and all hell's going to break loose if the baby isn't born lickety-split. Their concern is about babies growing too big for mom's pelvis, or a placenta growing too old to sustain a baby.
While those things do occasionally happen, they don't happen very often. Since post due date pregnancies put doctors on the defense legally speaking however, the birth culture pressed hard for women to accept medical interventions to push them into labor once the buzzer went off.
The thing is that prior to when all those crazy inductions took over the birth industry in the 80s and well into the s, women delivered safely a week or two past their due dates all the time and it was no big deal. There have been two studies that measured the average length of pregnancy using survival analysis: Study finds that estimated due date is 3 to 5 days AFTER 40 weeks In a very important study published in , Smith looked at the length of pregnancy in 1, healthy women whose estimated due dates, as calculated by the first day of the last menstrual period, were perfect matches with estimated due dates from their first trimester ultrasound Smith, a.
Study finds that estimated due date should be closer to 40 weeks and 5 days In , Jukic et al. So what was the average length of a pregnancy in this study? Are there some things that can make your pregnancy longer? Other factors that may make your pregnancy more likely to go longer include: Higher body mass index before you get pregnant Halloran et al. In , Caughey et al. The participants in this sample all gave birth at Kaiser Permanente hospitals in northern California. The overall use of interventions Cesareans and inductions in this sample was not listed.
The participants in this study were mostly well-educated. The rate of inductions was not listed. This was the same time period and same hospital as his study, but this time the researchers only looked at low-risk people who had health insurance. The overall Cesarean rate was The authors also took whether or not people had inductions into account when they calculated the risks of going past your due date Caughey et al.
Risks for mothers: The risk of chorioamnionitis infection of the membranes was lowest at 37 weeks 0. However, these numbers are much higher than are typically seen, and are partially related to the high use of vacuum and forceps in this study. What about the risk of stillbirth? There are two very important things for you to understand when learning about stillbirth rates. First, there is a difference between absolute risk and relative risk. Absolute risk is the actual risk of something happening to you.
Relative risk is the risk of something happening to you in comparison to somebody else. How do you measure stillbirth rates? Actual stillbirth rates vs. So what is the risk of stillbirth as you go past your due date? What factors can increase the risk of stillbirth?
Also, small for gestational age babies are often growth restricted at the week ultrasound. So, the gestational age for these babies is often under-estimated. This means that babies who are small for gestational age may be more post-term than we realize they are—increasing their risk while also leaving us unaware of their true gestational age Morken et al.
The traditional way of calculating the estimated due date 40 weeks after the last menstrual period is not evidence-based. This is more accurate than using the last menstrual period because it no longer assumes a Day 14 ovulation. An ultrasound before 20 weeks is usually more accurate than using the last menstrual period, and the accuracy of an ultrasound is highest if it is done between 11 and 14 weeks.
Changes to the estimated due date in late pregnancy should only be made in rare circumstances. Some individuals, such as first-time mothers, are at higher risk for experiencing stillbirth in late pregnancy than other individuals.
Committee opinion no. Obstet Gynecol , American College of Obstetricians and Gynecologists , Reaffirmed Committee Opinion No. Methods for Estimating the Due Date.
Ananth, C. A comparison of foetal and infant mortality in the United States and Canada. Int J Epidemiol 38 2 : Baskett, T. BJOG 11 : Boulvain, M. Prospective risk of stillbirth. Randomised trials of earlier induction of labour are needed.
BMJ : Caughey, A. Measuring perinatal complications: methodologic issues related to gestational age. BMC Pregnancy Childbirth 7: Complications of term pregnancies beyond 37 weeks of gestation. Obstet Gynecol 1 : What is the best measure of maternal complications of term pregnancy: ongoing pregnancies or pregnancies delivered?
Am J Obstet Gynecol 4 : Declercq, E. New York: Childbirth Connection. Divon, M. Male gender predisposes to prolongation of pregnancy. Flenady, V. Major risk factors for stillbirth in high-income countries: a systematic review and meta-analysis.
Lancet : Giscombe, C. Explaining disproportionately high rates of adverse birth outcomes among African Americans: the impact of stress, racism, and related factors in pregnancy. Psychol Bull 5 : Halloran, D. Effect of maternal weight on postterm delivery. J Perinatol 32 2 : Hilder, L. Prolonged pregnancy: evaluating gestation-specific risks of fetal and infant mortality.
Br J Obstet Gynaecol 2 : BMJ : ; author reply Huang, D. Determinants of unexplained antepartum fetal deaths. Obstet Gynecol 95 2 : Johnsen, S. Fetal size in the second trimester is associated with the duration of pregnancy, small fetuses having longer pregnancies.
BMC Pregnancy Childbirth 8: Jukic, A. Length of human pregnancy and contributors to its natural variation. Hum Reprod 28 10 : Khambalia, A. Predicting date of birth and examining the best time to date a pregnancy. Int J Gynaecol Obstet 2 : Kramer, M. Analysis of perinatal mortality and its components: time for a change?
Am J Epidemiol 6 : Maiti, K. Evidence that fetal death is associated with placental aging. Am J Obstet Gynecol, , Margerison-Zilko, C.
Postterm birth as a response to environmental stress : The case of September 11, Evol Med Public Health 1 : Mogren, I. Page last reviewed: 13 October Next review due: 13 October You and your baby at 37 weeks pregnant.
Your baby at 37 weeks At 37 weeks, your pregnancy is considered full-term. You at 37 weeks When you're around 37 weeks pregnant, if it's your first pregnancy, your baby moves down ready to be born.
Things to think about the signs of labour pain relief in labour , including things you can do yourself what happens at the hospital or birth centre and when to contact your antenatal team tips for your birth partner to support you during labour and birth what happens if your baby is breech , when a baby is born bottom first, which is more complicated than a head-first birth a caesarean , when you have surgery to deliver your baby the newborn blood spot heel prick test that will be offered to your baby The Start4Life site has more about you and your baby at 37 weeks pregnant.
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