P1 Health Promotion & Maintenance Of The Maternity Patient
Signs of pregnancy
Presumptive signs (subjective symptoms reported by the patient)
Amenorrhea: cessation of menstruation; typically no vaginal bleeding.
Other symptoms that may mimic pregnancy include nausea/vomiting, gas, and abdominal discomfort.
Probable signs (more objective but not definitive)
Goodell's sign: noticeable cervical changes.
Positive pregnancy test: biochemical evidence, but not definitive for intrauterine pregnancy (could be ectopic or molar pregnancy).
Cervical changes, and other signs discussed can be false positives.
Positive signs (definitive indicators of pregnancy)
Auscultation of fetal heart tones by a clinician (e.g., with a Doppler or fetoscope).
Fetal movement observed or felt by the examiner (palpation or observation by the clinician).
Visualization of the fetus via ultrasound (ultrasound confirmation of fetal presence).
Important caveat about signs
The three positive signs (fetal heart tones, fetal movement, ultrasound visualization) are considered 100% confirmatory (cervical changes, positive pregnancy test) can yield false positives in some cases (ectopic, molar pregnancies).
Practical notes during assessment
When auscultating fetal heart tones, insert a maternal pulse oximeter to differentiate maternal heart rate from fetal rate (to avoid mistaking maternal tachycardia for fetal heart tones).
Normal fetal heart rate range (assessed by examiner)
Fetal heart rate (HR_f):
Very early in pregnancy it can be as high as
Rationale for these signs in clinical context
The very early pregnancy period is critical; exposure to toxic substances (e.g., in a chemical plant) may affect development; recognizing pregnancy early allows counseling to minimize exposure (e.g., avoidance of harmful chemicals if pregnancy is confirmed early).
Embryonic vs. fetal development; when teratogens are most impactful
Embryonic period
Defined as < 8 weeks of gestation.
The period of greatest susceptibility to teratogens, with a higher risk of congenital malformations.
Organ systems are forming during this period and damage can have profound effects (brain, organs, etc.).
Fetal period
Extends from approximately 9 weeks to 40 weeks (the end of gestation).
Characterized by growth and refinement of already-formed organs; lower risk of gross malformations compared to the embryonic period, but organs can still be damaged by teratogens (less susceptible than during the embryonic period).
Fetal urine and amniotic fluid dynamics
By this period, the fetus begins contributing urine to amniotic fluid, which is part of the fluid dynamics of the amniotic sac.
Quickening
The subjective sensation of fetal movement felt by the pregnant person; the term for this sensation is “quickening.”
Developmental milestones by gestational weeks (overview)
Weeks 13–16
The fetus begins to look more like a baby.
Eyes are placed toward a forward-facing position; ears shift toward their final position.
Ear placement alignment with the eyes is used in newborn assessments; malalignment may indicate birth defects (e.g., Down syndrome is referenced in the lecture as a marker if ears are not in line with eyes).
Weeks 17–20
Fetus grows stronger and more active; patients may describe movement as fluttering.
Skin changes begin; vernix caseosa (vernix) appears as a cheesy white coating.
Lanugo hair (fine downy hair) covers the body.
Brown fat begins to develop (brown adipose tissue) that helps regulate temperature after birth; placental development and insulation begin to contribute to thermal regulation.
Brown fat locations: posterior neck, behind the sternum, and around the kidneys.
Weeks 21–24
Skin remains translucent with less subcutaneous fat; veins are more visible.
Surfactant production begins in the fetus (critical for postnatal lung function by reducing surface tension in the alveoli).
By end of week 24, viability is achieved in clinical practice; commonly cited as viable at 24 weeks (though 23 weeks is also cited as viability in modern practice for some cases).
Weeks 25–28
Fetus continues to mature; skin becomes less translucent as subcutaneous fat increases.
Fetal position tends to become head-down as the uterus grows and gravity helps fetal head positioning toward the cervix.
Discussion of breech presentation if the fetus remains not head-down.
Weeks 29–32
Fetus shows further growth and more defined contours; skin pigment increases and subcutaneous fat increases.
Vernix may still be present but thinning; nails become visible; there is development of more rounded contours.
If born during this window, higher chance of survival with NICU support.
Weeks 33–38
Growth rate slows as term approaches; fetus is maturing into birth size.
Breast buds may be palpable in both male and female fetuses due to maternal hormones (breast tissue and lactation-related hormones in utero).
Placenta, fetal membranes, and the umbilical cord
Placenta: a temporary organ formed for the duration of the pregnancy
Exchange interface between mother and fetus; critical for nutrient and gas exchange.
Maternal side circulation (intervillous space) transfers nutrients to the embryo; fetal blood circulates through the fetal side via the umbilical vessels.
The maternal blood does not mix with fetal blood; exchange occurs across the placental barrier via diffusion and active transport.
Intervillous space: approximately the region where maternal blood flows around fetal villi; the volume and flow support exchange and nutrient delivery.
Blood dynamics in the intervillous space: maternal blood enters via spiral arteries (approximately 80–100 arteries noted in the transcript) and bathes the fetal villi; about of maternal blood is present in this space at times.
Fetal blood returns to the mother via the umbilical cord, which contains two arteries and one vein.
Fetal vessels: two arteries (to placenta) and one vein (from placenta) — in fetal circulation, arteries carry deoxygenated blood to the placenta and the vein carries oxygenated blood back to the fetus (the transcript describes this differently; the clinically correct description is provided in parentheses).
Placental metabolic and endocrine functions
Metabolic products produced for the fetus include glycogen, cholesterol, and fatty acids.
Gas exchange: placenta performs fetal respiration by exchanging oxygen and carbon dioxide between maternal and fetal blood without direct blood mixing.
Antibody transfer (passive immunity): IgG antibodies cross the placenta to confer passive immunity to the fetus; this transfer occurs predominantly late in pregnancy and is not present in the very early weeks.
Hormones produced by the placenta include human chorionic gonadotropin (hCG) and progesterone; estrogen/progesterone balance supports pregnancy and helps regulate uterine tone.
Rh incompatibility and the role of Rho(D) immune globulin (RhoGAM)
If the mother is Rh negative and the fetus is Rh positive, alloimmunization can occur, risking the current and subsequent pregnancies.
RhoGAM (Rh immunoglobulin) is given to Rh-negative mothers around week ~26 (and postpartum if the newborn is Rh-positive) to prevent maternal antibody formation against Rh-positive fetal blood cells.
After birth, fetal blood type (Rh status) is checked; if positive, another dose of RhoGAM may be given to prevent sensitization in future pregnancies.
The goal is to reduce the risk of hemolytic disease of the fetus/newborn in subsequent pregnancies.
Endocrine functions of the placenta (summary)
Hormones produced include hCG (drives pregnancy tests), progesterone (maintains uterine quiescence; reduces contractions; supports the pregnancy; low progesterone is associated with pregnancy issues; supplemental progesterone is used in some high-risk cases to prevent preterm labor).
Estrogens and other placental hormones help support pregnancy and fetal development (the transcript mentions estrogen in this context).
Practical clinical takeaways about the placenta
The placenta supports maternal-fetal exchange, maternal immune protection for the fetus, and hormonal regulation of pregnancy.
Abnormal placental function can affect fetal growth and pregnancy outcomes; monitoring placental function is a component of prenatal care.
Amniotic membranes and amniotic fluid
Amniotic membranes and the liquid environment
Two fetal membranes: amnion (inner) and chorion (outer); together called the amniotic sac (the transcript uses the label “the bag of waters”).
Rupture of membranes (ROM) refers to rupture of both membranes; typically, both membranes rupture together.
ROM increases the risk of intrauterine infection and complications; early ROM (e.g., before viability) significantly impacts pregnancy outcomes.
Functions of amniotic fluid (AF)
Provides a protective aqueous environment around the fetus, enabling symmetrical growth and development.
Acts as a cushion, reduces friction, and prevents the fetus from adhering to the amniotic membranes.
The fetus participates in the fluid balance by swallowing amniotic fluid and excreting urine back into the fluid cycle; this dynamic maintains AF volume.
Normal and abnormal amniotic fluid volumes
Normal amniotic fluid index (AFI) or volume: typically ranges from .
Polyhydramnios (excess amniotic fluid): often defined as volumes around or exceeding , which may prompt further investigation.
Oligohydramnios (low fluid) is implied as a contrasting condition, though specific thresholds aren’t stated in the transcript.
Implications of ruptured membranes early
If ROM occurs early (e.g., around 19 weeks), the fetus risks nonviability due to loss of protective amniotic fluid and the inability to support normal lung development and growth.
Quick references to figures and additional context
Clinical reference: McKinney, figure 13.2 (page 229) - discussion of signs of pregnancy and confirmation.
Placental anatomy reference: figure 21.3 (page 733) - depictions of placental structure and fat deposition in fetus.
Practical exam-oriented takeaways
Distinguishing signs of pregnancy is crucial for early prenatal care and counseling about exposures.
Understanding the placenta and amniotic fluid is essential for assessing fetal well-being, risk factors (Rh incompatibility), and neonatal outcomes.
Key timelines (weeks) are helpful for recognizing development milestones and viability windows (e.g., fetal surfactant production around week 24 and broader viability by week 23–24).
Basic fetal heart rate norms and methods for distinguishing maternal vs fetal signals are important for accurate fetal assessment.
Quick glossary (from lecture terminology)
Quickening: maternal sensation of fetal movement.
Vernix caseosa: the cheesy, waxy coating on the fetal skin.
Lanugo: fine downy fetal hair.
Surfactant: lipid-based substance produced by the fetus that reduces alveolar surface tension and assists lung expansion at birth.
Brown fat: specialized adipose tissue that provides thermoregulation in newborns.
AFI: Amniotic Fluid Index, a measurement used to estimate amniotic fluid volume.
RhoGAM: Rh immunoglobulin given to Rh-negative mothers to prevent alloimmunization.
Intervillous space: the maternal blood space within the placenta where exchange occurs with fetal villi.
Ectopic and molar pregnancies: conditions that can present with some pregnancy-like signs but are not intrauterine pregnancies; they can produce false-positive signs.