Childbirth~
that incredible human occurrence that causes joy and fear, avoidance and
intrigue. A woman’s body is uniquely
designed to conceive, nourish and bring forth another human life. But does Mother Nature need help? That MUCH help that an estimated 20% of US
women are induced yearly?1
This rate is important. Since
1982, the American College of Obstetricians and Gynecologists (ACOG) have had
specific guidelines in place that recommend against elective inductions in
early term or before 39 weeks 5.
Similarly, the Association of Womens Health, Obstetrics and Neonatal
Nursing (AWHONN) plus the March of Dimes have campaigns to make the public
aware that babies should be growing inside the Mother’s uterus for as long as
possible.
So how long is a pregnancy?
If
you count nine months and each month has 4 weeks, you count 36 weeks through
simple math. However, estimating
gestational age is not that easy. Called
Naegele’s Rule, the expected date of delivery (EDD)
is calculated by adding one year, subtracting three months, and adding seven
days to the first day of a woman's last menstrual period (LMP). The
result is approximately 280 days (40 weeks) from the LMP. And the EDD or Due Date is an ESTIMATE. Each woman with each pregnancy gestates their
babies differently with approximate variation of up to five weeks.2
How does labor begin?
hCG: The early chorionic villi of the implanted ovum secrete human
chorionic gonadotropin (hCG), which prolongs the life of the corpus luteum. The
result is the continued production of estrogen and progesterone, which are
necessary to maintain the endometrium. During pregnancy, hCG appears in
maternal blood and is excreted in the mother's urine, allowing diagnosis of
pregnancy by tests.
hPL: The chorionic cells of the placenta produce another hormone,
human chorionic somatomammotropin which is also known as human placental
lactogen (hPL). This hormone influences somatic cell growth of the fetus and
facilitates preparation of the breasts for lactation.
The increase in hCG and hPL in the mother is thought to be
responsible for many important changes during pregnancy such as growth of the
uterus and the development of the breast duct system. Estrogen is
also helpful in breast duct system development and progesterone is valuable in
the development of the lobule-alveolar system.
The pituitary gland enlarges during pregnancy and is the source
of production of oxytocin. The posterior lobe is the primary source
of oxytocin, which has a stimulating effect on the uterine muscle and
lactation.
The adrenal cortex increases in activity during pregnancy. The
secretion of cortisol by the adrenals does not change yet the
metabolism of cortisol is changed as a result of estrogen. There is an increase
in aldosterone production by the adrenal glands and this
hormone results in the decreased ability of the kidneys to handle salt during
pregnancy. This leads to some fluid retention or edema.
Relaxin is produced by the ovaries and is primarily responsible
for softening ligaments and cartilage. The softening of cartilage, especially
in late pregnancy, is the cause of suprapubic discomfort, waddling, and the
ability of the pelvis to spread during the birth process.
What happens when induction happens too soon?
For Babies: Organs such as brain, lungs and liver need ample
time to develop ~ up to 39/40 weeks!
Babies born at 39+ weeks are less likely to have vision or hearing
problems, have an easier time staying warm and can suck/swallow and eat better.6
For Mothers: induction of labor causes contractions that are
characteristically harder, stronger and closer together than the normal
progression of labor, making labor more difficult with which to cope. There are higher risks of infection and
uterine tears/rupture. Inductions may
not work if there are not sufficient oxytocin receptor sites on the uterus. Oxytocin receptor sites are developed through
the pregnancy and are necessary to receive the oxytocin that the body
produces. If there are insufficient
oxytocin receptor sites, neither mother’s naturally-produced oxytocin nor the
artificial oxytocin or Pitocin, will take effect. Thus, with a “failed induction” a cesarean
section occurs.3,6
AWHONN
has a list of reasons – 40 of them – as to why a pregnancy should go the full
40 weeks. You can access and print the
pdf article for distribution by clicking here.
Diligence must be
exercised when monitoring labor and fetal well-being. Hofbauer, the first
to use oxytocin to induce labor, said in 1927 that oxytocin, "with its power of
producing regular, rhythmical and forcible uterine contractions, should be
regarded as a most beneficent and valuable agent, which, however, should always
be employed with care and a realisation of its limitations and dangers." His words
remain valid today.4
References:
2. http://www.ctvnews.ca/health/length-of-human-pregnancies-varies-by-five-weeks-study-says-1.1401629
3. Smith, L. (2012) Impact
of Birthing Practices on Breastfeeding (2nd Edition).
4. Diligence Shyken,
J.M. et al. (1995) Oxytocin to induce labor.
Clinical Obstetrics and Gynecology. June, 38(2):232-45.
5. ACOG https://www.acog.org/About_ACOG/ACOG_Departments/Deliveries_Before_39_Weeks
6. http://www.marchofdimes.com/pregnancy/why-at-least-39-weeks-is-best-for-your-baby.aspx