Maternal Adaptations During Pregnancy

Maternal Adaptation During Pregnancy: Chapter 11 Study Notes

Learning Objectives

• Differentiate between presumptive (subjective), probable (objective), and positive (diagnostic) signs of pregnancy.

• Describe the maternal physiologic changes that occur during pregnancy.

• Summarize the nutritional needs of the pregnant woman and her fetus.

• Characterize the emotional and psychological changes that occur during pregnancy.

Signs of Pregnancy

Presumptive Signs (Subjective)

These are symptoms experienced by the woman that may indicate pregnancy but can also be attributed to other conditions. They are the least reliable indicators.

• Fatigue: ($12$ weeks)

• Breast tenderness: ($3$ to $4$ weeks)

• Nausea and vomiting: ($4$ to $14$ weeks)

• Amenorrhea: (Absence of menstruation) ($4$ weeks)

• Urinary frequency: ($6$ to $12$ weeks)

• Hyperpigmentation of skin: ($16$ weeks) - includes the mask of pregnancy and linea nigra.

• Fetal movements (quickening): ($16$ to $20$ weeks) - the woman feeling fetal movement.

• Uterine enlargement: ($7$ to $12$ weeks)

• Breast enlargement: ($6$ weeks)

Probable Signs (Objective)

These are observed by the examiner, are more objective, but still do not definitively confirm pregnancy as they can be caused by other conditions.

• Braxton Hicks contractions: ($16$ to $28$ weeks) - irregular, generally painless uterine contractions.

• Positive pregnancy test: ($4$ to $12$ weeks) - detects human chorionic gonadotropin (hCG), but false positives can occur.

• Abdominal enlargement: ($14$ weeks)

• Ballottement: ($16$ to $28$ weeks) - the passive movement of the unengaged fetus when tapped by the examiner's finger during a vaginal examination.

• Goodell sign: (Softening of the cervix) ($5$ weeks)

• Chadwick sign: (Bluish-purple coloration of the vaginal mucosa and cervix) ($6$ to $8$ weeks) - due to increased vascularity.

• Hegar sign: (Softening of the lower uterine segment or isthmus) ($6$ to $12$ weeks)

Definitions of Key Signs

• Chadwick sign: Bluish-purple coloration of the vaginal mucosa and cervix, appearing at $6$ to $8$ weeks, caused by increased vascularity.

• Goodell sign: Softening of the cervix, typically noted around $5$ weeks.

• Hegar sign: Softening of the lower uterine segment or isthmus, observed around $6$ to $12$ weeks.

Select Pregnancy Tests

Positive Signs (Diagnostic)

These signs are unequivocally attributed to the presence of a fetus and confirm pregnancy definitively.

• Ultrasound verification of embryo or fetus: (4$to$6$weeks) - visualization of the gestational sac, fetal pole, or heartbeat.</p></li><li><p><strong>Fetal movement felt by experienced clinician:</strong> ($20$weeks) - palpation of fetal movement is distinct from quickening.</p></li><li><p><strong>Auscultation of fetal heart tones via Doppler:</strong> ($10$to$12$weeks) - hearing the fetal heartbeat.</p></li></ul><h4 id="3635cd47-0fa5-4887-9526-cc3e930afcf1" data-toc-id="3635cd47-0fa5-4887-9526-cc3e930afcf1" collapsed="false" seolevelmigrated="true">Maternal Physiologic Adaptations During Pregnancy</h4><h5 id="72214400-b402-4440-806c-2b470570f0e9" data-toc-id="72214400-b402-4440-806c-2b470570f0e9" collapsed="false" seolevelmigrated="true">Reproductive System Adaptations</h5><ul><li><p><strong>Uterus:</strong></p><ul><li><p>Increase in size, weight, length, width, depth, volume, and overall capacity.</p></li><li><p>Changes from a pear shape to an ovoid shape.</p></li><li><p>Positive Hegar sign due to softening of the lower uterine segment.</p></li><li><p>Enhanced uterine contractility, leading to Braxton Hicks contractions.</p></li><li><p>Ascends into the abdomen after the first$3$months.</p></li><li><p>Fundal height at$20$weeks' gestation is typically at the level of the umbilicus, measuring approximately$20$cm; this measurement is a reliable determination of gestational age until$36$weeks' gestation.</p></li></ul></li><li><p><strong>Cervix:</strong></p><ul><li><p>Softening (Goodell sign).</p></li><li><p>Formation of a mucus plug (operculum) which seals off the uterus, protecting against infection.</p></li><li><p>Increased vascularization (Chadwick sign).</p></li><li><p>Ripening (softening and effacement) about$4$weeks before birth in preparation for labor.</p></li></ul></li><li><p><strong>Vagina:</strong></p><ul><li><p>Increased vascularity and thickening of the mucosa.</p></li><li><p>Lengthening of the vaginal vault.</p></li><li><p>Secretions become more acidic, white, and thick, known as leukorrhea; this helps prevent bacterial infections but also increases susceptibility to yeast infections.</p></li></ul></li><li><p><strong>Ovaries:</strong></p><ul><li><p>Enlarge until the$12^{\text{th}}$to$14^{\text{th}}$week of gestation.</p></li><li><p>Cessation of ovulation (due to hormonal suppression of FSH and LH).</p></li></ul></li><li><p><strong>Breasts:</strong></p><ul><li><p>Increase in size and nodularity to prepare for lactation.</p></li><li><p>Increase in nipple size, becoming more erect and pigmented.</p></li><li><p>Production of colostrum: an antibody-rich, yellow fluid that can be expressed after the$12^{\text{th}}$week of pregnancy. It converts to mature milk after delivery.</p></li></ul></li></ul><h5 id="4ad0948e-0d35-4266-a211-cee70a591970" data-toc-id="4ad0948e-0d35-4266-a211-cee70a591970" collapsed="false" seolevelmigrated="true">Gastrointestinal Adaptations</h5><ul><li><p><strong>Gums:</strong> Become hyperemic (increased blood flow), swollen, and friable (easily bleeding).</p></li><li><p><strong>Ptyalism:</strong> Increased salivation, often due to decreased swallowing of saliva.</p></li><li><p><strong>Dental problems:</strong> Increased risk of gingivitis and dental issues due to hormonal changes.</p></li><li><p><strong>Decreased peristalsis and smooth muscle relaxation:</strong> Primarily due to increased progesterone.</p></li><li><p><strong>Constipation:</strong> A common side effect of decreased peristalsis, exacerbated by increased venous pressure and pressure from the enlarging uterus, leading to.</p></li><li><p><strong>Hemorrhoids:</strong> Varicosities of the rectal veins.</p></li><li><p><strong>Slowed gastric emptying:</strong> Contributes to feelings of fullness and can exacerbate.</p></li><li><p><strong>Heartburn:</strong> Gastroesophageal reflux due to relaxation of the lower esophageal sphincter.</p></li><li><p><strong>Prolonged gallbladder emptying:</strong> Can lead to gallbladder stasis and increased risk of gallstone formation.</p></li><li><p><strong>Nausea and vomiting:</strong> Especially prominent in the first trimester (morning sickness), influenced by hCG levels and hormonal changes.</p></li></ul><h5 id="5af90029-f581-49f0-b133-d3d0f1ec3d42" data-toc-id="5af90029-f581-49f0-b133-d3d0f1ec3d42" collapsed="false" seolevelmigrated="true">Cardiovascular Adaptations</h5><ul><li><p><strong>Increase in blood volume:</strong> By$30-50$%.

• Increase in cardiac output: By 30-50$% due to increased venous return and increased stroke volume.

• Increased heart rate: By 10-20$beats per minute.</p></li><li><p><strong>Slight decline in blood pressure:</strong> Typically until mid-pregnancy, then returning to pre-pregnancy levels.</p></li><li><p><strong>Increase in number of RBCs:</strong> But plasma volume increases even more, leading to hemodilution (physiologic anemia of pregnancy).</p></li><li><p><strong>Increase in iron demands:</strong> To support expanded blood volume and fetal needs.</p></li><li><p><strong>Increase in fibrin and plasma fibrinogen levels, and some clotting factors:</strong> Leading to a hypercoagulable state, which is a protective mechanism against postpartum hemorrhage but also increases the risk of thromboembolic events.</p></li></ul><h5 id="9efbf14d-76d3-4328-b3f3-ad2b613efa3a" data-toc-id="9efbf14d-76d3-4328-b3f3-ad2b613efa3a" collapsed="false" seolevelmigrated="true">Respiratory System Adaptations</h5><ul><li><p><strong>Breathing becomes more diaphragmatic than abdominal:</strong> Due to an increase in diaphragmatic excursion, chest circumference, and tidal volume.</p></li><li><p><strong>Increase in oxygen consumption:</strong> By$15-20$% to meet the metabolic demands of pregnancy.

• Congestion: Secondary to increased vascularity in the upper respiratory tract, often leading to nasal stuffiness and epistaxis (nosebleeds).

Renal & Urinary Adaptations

• Dilation of renal pelvis: Along with elongation, widening, and an increase in the curve of the ureters, which can increase the risk of urinary tract infections.

• Increase in length and weight of kidneys.

• Increase in Glomerular Filtration Rate (GFR): By 30-50$% leading to an increased urine flow and volume.

• Increase in kidney activity: When the woman lies down, with an even greater increase in later pregnancy when the woman lies on her side, improving renal perfusion.

Musculoskeletal System Adaptations

• Softening and stretching of ligaments: Particularly those holding the sacroiliac joints and pubis symphysis, primarily due to the hormone relaxin, preparing the pelvis for birth.

• Postural changes: Including increased swayback (lumbar lordosis) and upper spine extension to compensate for the shifting center of gravity.

• Forward shifting of the center of gravity.

• Increase in lumbosacral curve (lordosis): Caused by the enlarging uterus, leading to lower back pain.

• Compensatory curve in the cervicodorsal area: To maintain balance.

• Waddle gait: A characteristic altered gait resulting from the loosened pelvic joints and changing center of gravity.

Integumentary System Adaptations

• Hyperpigmentation: Increased melanin production, leading to darkening of certain areas.

  • Mask of pregnancy (chloasma/melasma gravidarum): Darkening of skin on the face, especially on the forehead, cheeks, and nose.

  • Linea nigra: Darkening of the line extending from the umbilicus to the pubic area.

• Striae gravidarum (stretch marks): Reddish or purple lines on the abdomen, breasts, and thighs due to the stretching of connective tissue; they typically fade to silvery-white post-delivery.

• Varicosities: Enlarged, twisted veins, commonly in the legs, vulva, and rectum (hemorrhoids), due to increased venous pressure and progesterone effects.

• Vascular spiders (spider nevi): Small, bright red elevations on the skin consisting of a central arteriole with radiating fine capillaries, often on the neck, thorax, face, and arms.

• Palmar erythema: Redness of the palms of the hands and soles of the feet, caused by increased estrogen levels.

• Decline in hair growth: Often seen postpartum as hormonal levels normalize.

• Increase in nail growth: Nails may become stronger or more brittle.

Endocrine System Adaptations

• Thyroid Gland:

  • Slight enlargement and increased activity.

  • Increase in Basal Metabolic Rate (BMR) by 20-25$%.

• Pituitary Gland:

  • Enlargement.

  • Decrease in Thyroid-Stimulating Hormone (TSH) and Growth Hormone (GH).

  • Inhibition of Follicle-Stimulating Hormone (FSH) and Luteinizing Hormone (LH) to prevent ovulation.

  • Increase in prolactin (for lactation preparation) and Melanocyte-Stimulating Hormone (MSH) (contributes to hyperpigmentation).

  • Gradual increase in oxytocin with fetal maturation, playing a role in labor onset and postpartum contractions.

• Pancreas:

  • Develops insulin resistance due to the effects of Human Placental Lactogen (hPL) and other hormones in the second half of pregnancy, ensuring a greater glucose supply for the fetus. This can lead to gestational diabetes.

• Adrenal Glands:

  • Increase in cortisol and aldosterone secretion.

  • Cortisol helps regulate carbohydrate and protein metabolism.

  • Aldosterone regulates fluid and electrolyte balance.

• Prostaglandin secretion: Plays various roles, including cervical ripening and uterine contractility.

• Placental Secretion: Produces crucial hormones.

  • Human Chorionic Gonadotropin (hCG): Maintains the corpus luteum, which produces progesterone and estrogen until the placenta takes over.

  • Human Placental Lactogen (hPL): Also known as chorionic somatomammotropin, influences maternal metabolism to ensure nutrient supply to the fetus; contributes to insulin resistance.

  • Relaxin: Softens ligaments and cartilage in the pelvis.

  • Progesterone: Critical for maintaining pregnancy by decreasing uterine contractility and relaxing other smooth muscles.

  • Estrogen: Stimulates uterine growth and uteroplacental blood flow; promotes breast development.

Nutritional Needs of the Pregnant Woman and Her Fetus

• Direct effect of nutritional intake: On fetal well-being and birth outcome.

• Need for vitamin and mineral supplements: A daily prenatal vitamin is essential.

• Dietary recommendations:

  • Increase in protein, iron, folate, and calories.

  • Folate (folic acid) is crucial for preventing neural tube defects; recommended intake is $400$ micrograms ($ext{mcg}$) daily before conception and $600$($ext{mcg}$) daily during pregnancy.

  • Iron is needed to support expanded maternal blood volume and fetal red blood cell production; supplementation is often required.

  • Calories: An increase of approximately $300$ extra calories per day in the second and third trimesters.

• Use of USDA’s Food Guide MyPlate: Provides general guidance for healthy eating.

• Avoidance of some fish: Due to potential mercury content (e.g., shark, swordfish, king mackerel, tilefish).

Maternal Weight Gain

Recommended total weight gain varies based on pre-pregnancy Body Mass Index (BMI).

• Healthy Weight BMI ($18.5 - 24.9$): Recommended total gain of $25$ to $35$ lb ($11.5 - 16$ kg).

  • First trimester: $3.5$ to $5$ lb ($1.6 - 2.3$ kg).

  • Second and third trimesters: Approximately $1$ lb/wk ($0.45$ kg/wk).

• BMI <19.8 (Underweight): Recommended total gain of $28$ to $40$ lb ($12.7 - 18.1$ kg).

  • First trimester: Approximately $5$ lb ($2.3$ kg).

  • Second and third trimesters: $+1$ lb/wk ($0.45$ kg/wk).

• BMI >25 (Overweight/Obese): Recommended total gain of $15$ to $25$ lb ($6.8 - 11.3$ kg).

  • First trimester: Approximately $2$ lb ($0.9$ kg).

  • Second and third trimesters: Approximately $2/3$ lb/wk ($0.3$ kg/wk).

Maternal Emotional and Psychological Changes During Pregnancy

• Ambivalence: Conflicting feelings about pregnancy, which is a normal response.

• Introversion: A focus on oneself and one's body, often seen in early pregnancy.

• Acceptance: Growing acceptance of the pregnancy and the unborn child.

• Mood swings: Hormonal fluctuations and physical discomforts can lead to emotional lability.

• Changes in body image: Adjusting to the physical changes of pregnancy, which can impact self-esteem.

Maternal Roles and Tasks

According to Rubin's maternal tasks (though not explicitly named in transcript, these points align):

• Ensuring safe passage: Throughout pregnancy and birth for herself and her unborn child.

• Seeking acceptance of infant by others: The partner, family, and friends.

• Seeking acceptance of self in maternal role to infant: Developing a bond and preparing for motherhood.

• Learning to give of oneself: Understanding the sacrifices and unconditional love required for parenting.

Pregnancy and Sexuality

• Numerous changes: Can potentially stress the sexual relationship with the partner.

• Changes in sexual desire: Varies with each trimester, often influenced by hormones, fatigue, and discomfort.

• Sexual health and link to self-image: Perceptions of attractiveness and comfort with physical changes can impact sexual desire and activity.

Pregnancy and the Partner

• Family-centered emphasis: Modern maternity care recognizes the partner's crucial role.

• Partner’s reaction to pregnancy and changes: Can range from excitement to anxiety or ambivalence.

• Couvade Syndrome: Experiencing pregnancy-like symptoms (e.g., weight gain, nausea) without being pregnant, a phenomenon seen in some expectant fathers.

• Ambivalence: Partners can also experience conflicting feelings about the pregnancy.

• Acceptance of roles: Typically solidifies in the second trimester as the pregnancy becomes more real.

• Preparation for reality of new role: Intensifies in the third trimester as birth approaches.

Pregnancy and Siblings

• Age-dependent reaction: Children's responses vary greatly with their developmental stage.

  • Younger children may be confused or show regression.

  • Older children may be more understanding but still experience jealousy.

• Sibling rivalry: A common occurrence with the introduction of a new infant into the family.

• Sibling preparation imperative: Involving siblings in pregnancy preparations helps them adjust and accept the new baby.