In active labor contractions continue to
increase in frequency and intensity, and discom-
fort progresses to PAIN. Many women feel the need
for pain relief during active labor. Common meth-
ods include narcotic ANALGESIC MEDICATIONS and
regional ANESTHESIAsuch as epidural block. Active
labor dilates the cervix to 7 or 8 centimeters.
The final stage of labor is transition, during
which contractions come in waves often without
more than seconds between them. Transition con-
sumes the woman’s attention and focus; she often
is not aware of activity taking place around her.
Many women feel the urge to push, though
should not do so because the cervix is not yet
ready. Transition is usually complete within three
hours. The cervix finishes dilating to a wide-open
10 centimeters, and birth is imminent.
Stage 2: Delivery of the Baby
Delivery requires much conscious effort from the
woman to push with contractions. The birthing
team coaches and guides the process. The urge to
push may be overwhelming; going with it is usu-
ally the most efficient approach unless the doctor
or midwife advises to wait. Sometimes the baby’s
position in the birth canal becomes awkward such
that waiting a few moments allows a turn or
movement that then responds better to pushing.
An epidural for pain relief tends to extend deliv-
ery somewhat because the woman does not as
strongly feel the urge to push.
The head emerges first, with the shoulders and
then the rest of the body following. The doctor or
midwife suctions any mucus and BLOODfrom the
baby’s NOSEand MOUTH. The baby begins breathing
as soon as his or her body clears the birth canal
and the chest can expand. When all is well, the
doctor or midwife places the baby on the mother’s
chest for her to hold and clamps the UMBILICAL
CORDin two places. The partner, the mother, an
older sibling present for the birth, or the birthing
attendant may cut between the clamps to sever
the cord.
Stage 3: Delivery of the Placenta
After a brief pause contractions resume to separate
the PLACENTAfrom the endometrium and push it
from the body. It takes about 10 minutes to
deliver the placenta, which sometimes requires
the woman to bear down to help push it out. The
uterus then continues mild contractions, which
are important to restore its firmness and to stop
bleeding. A member of the birthing team may
massage the mother’s lower abdomen to further
stimulate these contractions. BREASTFEEDING the
infant at this time is also helpful because the suck-
ing at the BREASTreleases OXYTOCIN, a HORMONEthat
continues the uterine contractions as well as
releases colostrum (premilk) for the infant.
For further discussion of childbirth, please see
the overview section “The Reproductive System.”
See also POSTPARTUM DEPRESSION; PRENATAL CARE;
VBAC.chordee A congenital (present at birth) down-
ward curvature of the PENIS. Chordee results from
extra connective tissue that contracts the ventral
surface of the penis, pulling the tip of the penis
downward. Chordee typically occurs in conjunc-
tion with HYPOSPADIAS, a CONGENITAL ANOMALY in
which the opening of the URETHRA(the meatus) is
on the underside of the penis rather than at the
tip. Chordee may be apparent only during EREC-
TION or may contract the penis significantly
enough to prevent normal URINATION. Mild
chordee that does not interfere with urination or
SEXUAL INTERCOURSE does not require treatment.
For more severe chordee, surgery to release the
connective tissue and, if necessary, to correct the
hypospadias relieves the curvature.
See also CIRCUMCISION; PEYRONIE’S DISEASE; PHIMO-
SIS; SURGERY BENEFIT AND RISK ASSESSMENT.chorionic villi sampling (CVS) A diagnostic pro-
cedure, also called chorionic villus sampling, in
which the obstetrician removes small clusters of
cells from the hairlike edges of the PLACENTA, the
chorionic villi, during PREGNANCY. The cells in this
sample provide genetic information about the
FETUSthat can rule out or diagnose GENETIC DISOR-
DERSsuch as CYSTIC FIBROSISand TAY-SACHS DISEASE,
NEURAL TUBE DEFECTSsuch as SPINA BIFIDA, or CHRO-
MOSOMAL DISORDERSsuch as DOWN SYNDROME. The
obstetrician can perform CVS in the first trimester,
usually around the 11th week, providing informa-
tion about potential health concerns early in the
pregnancy to allow the woman and her partner to
consider possible treatment options as well as262 The Reproductive System