and Clinical Application
Jennie, a freshman in your dormitory, tells you she just discovered
that she is three months pregnant. She recently bragged that since
she came to college she has been drinking alcohol heavily and
experimenting with every kind of recreational drug she could
ﬁnd. From the following, select the advice you would give her,
and explain why it is the best choice. (a) She must stop taking
drugs, but they could not have aﬀected her fetus during these ﬁrst
few months of her pregnancy. (b) Harmful substances usually
cannot pass from mother to embryo, so she can keep using drugs.
(c) Tere could be defects in the fetus, so she should stop using
drugs and visit a doctor as soon as possible. (d) If she has not
taken any drugs in the last week, she is okay.
During Mrs. Jones’s labor, the obstetrician decided that it was
necessary to perform an episiotomy. What is an episiotomy, and
why is it done?
A woman in substantial pain called her doctor and explained
(between sobs) that she was about to have her baby “right here.”
Te doctor calmed her and asked how she had come to that
conclusion. She said that her water had broken and that her
husband could see the baby’s head. (a) Was she right? If so, what
stage of labor was she in? (b) Do you think that she had time to
make it to the hospital 60 miles away? Why or why not?
Mary is a heavy smoker and has ignored a friend’s advice to stop
smoking during her pregnancy. On the basis of what you know
about the eﬀect of smoking on physiology, describe how Mary’s
smoking might aﬀect her fetus.
While Mortimer was cramming for his anatomy test, he read that
some parts of the mesoderm become segmented. He suddenly
realized that he could not remember what segmentation is.
Deﬁne segmentation, and give two examples of segmented
structures in the embryo.
Assume a sperm has penetrated a polar body and their nuclei
fuse. Why would it be unlikely for the resulting cell to develop
into a healthy embryo?
Related Clinical Terms
born prematurely) ±ermination of a pregnancy
that is in progress; may be spontaneous or induced.
outside) A pregnancy in which
the embryo implants in any site other than the uterus; most o²en
the site is a uterine tube (tubal pregnancy). Since the uterine
tube (as well as most other ectopic sites) is unable to establish
a placenta or accommodate growth, the uterine tube ruptures
unless the condition is diagnosed early, or the pregnancy
Hydatid (hydatidiform) mole
Developmental abnormality of the placenta; the conceptus
degenerates and the chorionic villi convert into a mass of vesicles
that resemble tapioca. Signs include vaginal bleeding, which
contains some of the grapelike vesicles.
dis) Jaundice sometimes occurring
in normal newborns within three to four days a²er birth. Fetal
erythrocytes are short-lived, and they break down rapidly a²er
birth; the infant’s liver may be unable to process the bilirubin
(breakdown product of hemoglobin pigment) fast enough to
prevent its accumulation in blood and subsequent deposit in
broken away from)
Premature separation of the placenta from the uterine wall; if
this occurs before labor, it can result in fetal death due to anoxia.
ve-ah) Placental formation adjacent to or across
the internal os of the uterus. Represents a problem because as the
uterus and cervix stretch, separation of the placenta may occur.
Additionally, the placenta precedes the infant during labor.
rah-fe) Noninvasive technique that
uses sound waves to visualize the position and size of the fetus
and placenta (see
A Closer Look
, Chapter 1).
AT T H E C L I N I C
When paramedics arrived on the crash
scene on Route 91, they found Maria
Rodriguez, a 34-year-old female,
lying on the edge of the road. Mrs.
Rodriguez was responsive, but had deep lacerations on both legs
and her right arm. Her clothes were heavily stained with blood,
despite the efforts of another passenger to slow the bleeding by
applying compression. On initial examination, Mrs. Rodriguez’s blood
pressure was 100/70 with a heart rate of 88. The paramedics started
an IV of normal saline, stabilized her, and controlled the bleeding
during transport to the hospital. Mrs. Rodriguez was released from
the hospital three days later and scheduled for a follow-up visit in
one week. At her follow-up appointment, she complained of fatigue
and reported that her period was overdue by one week. Hospital
blood tests revealed that Mrs. Rodriguez was mildly anemic—and
pregnant. While she was excited, she was also very concerned that
the blood loss she suffered may have harmed her baby.
What hormone did the hospital detect in Mrs. Rodriguez’s
blood to determine that she was pregnant?
Where is the hormone made that you identiﬁed in question 1?
What function does it play during the early stages of a pregnancy?
Mrs. Rodriguez’s doctors explained that the blood loss she
suffered as a result of the accident occurred approximately
10–12 days after her most recent ovulation. Explain why this
may help ease Mrs. Rodriguez’s fears about harm to her baby.
Describe the major developmental events and stages of
embryonic development that have occurred during the time
prior to Mrs. Rodriguez’s accident.
Mrs. Rodriguez is currently in the third week of pregnancy.
Describe the important embryonic developmental event that
occurs during this time.
(Answers in Appendix H)