What are the maternal physiologic changes, signs, and symptoms of pregnancy, including morning sickness, and how do they affect daily routine and occupation, particularly for a working manager at 6 weeks and 2/7 days gestation?

Maternal Physiologic Changes and Early Pregnancy Symptoms at 6 Weeks Gestation

A. Maternal Physiologic Changes During Pregnancy Trimesters

Cardiovascular adaptations begin in early pregnancy and progress throughout gestation, with cardiac output increasing 30-50% by 32 weeks and plasma volume expanding by approximately 50%. 1, 2

First Trimester (Weeks 1-13)

• Cardiac output begins increasing early, driven primarily by stroke volume elevation and a modest heart rate increase of 10-20 bpm 1, 2
• Peripheral vasodilation occurs due to endothelium-dependent factors, causing systemic vascular resistance to fall 1
• Blood pressure decreases by 10-15 mmHg by 20 weeks due to vasodilation, then returns to pre-pregnancy levels by term 1
• Functional residual capacity decreases by 10-25% as the uterus begins enlarging and elevating the diaphragm 3
• Progesterone increases minute ventilation by 20-40% above baseline, producing mild compensated respiratory alkalosis 2
• Plasma albumin concentration decreases, affecting drug binding and distribution 4

Second Trimester (Weeks 14-27)

• Cardiac output continues rising, reaching near-maximum levels with increased stroke volume as the primary driver 2
• Uteroplacental blood flow increases dramatically from 50 mL/min to approaching 1000 mL/min, receiving up to 20% of maternal cardiac output at term 2
• Renal blood flow and glomerular filtration rate increase by 40-50% by 24 weeks gestation 5
• The enlarging uterus elevates the diaphragm further and can compress the inferior vena cava in supine position, potentially decreasing venous return 2
• Left lateral positioning becomes important to optimize cardiac output by relieving vena caval compression 2

Third Trimester (Weeks 28-40)

• Cardiac output reaches maximum at 32 weeks (40-50% above baseline), maintained through both increased stroke volume and heart rate 1, 2
• Blood volume expansion is complete with plasma volume increased by 50% and red blood cell mass increased proportionally 2
• Oxygen consumption increases 20-33% above baseline due to fetal demands and maternal metabolic processes 3
• The oxyhemoglobin dissociation curve shifts to the right, requiring higher partial pressure of oxygen to achieve the same maternal oxygen saturation 3
• Physiologic changes are most pronounced in this trimester, affecting drug disposition and clinical assessment 4, 6

Labor and Immediate Postpartum

• Cardiac output rises further during labor as uterine contractions cause autotransfusion of 300-500 mL blood back to circulation 1
• Sympathetic response to pain increases heart rate during contractions 1
• Some physiologic changes normalize within 24 hours of delivery, while others persist up to 12 weeks postpartum 4

---

B. Signs and Symptoms of Pregnancy with Clinical Correlations

Common Early Pregnancy Symptoms

Nausea and vomiting of pregnancy (NVP) affects 30-90% of pregnant women, typically beginning at 4-6 weeks, peaking at 8-12 weeks, and subsiding by week 20. 1

Nausea and Vomiting of Pregnancy (NVP)

• NVP is associated with elevated human chorionic gonadotropin and estrogen levels and changes in gastrointestinal motility 1
• Progesterone inhibits GI and small bowel motility, leading to delayed gastric emptying 1
• Severity can be quantified using the Motherisk Pregnancy-Unique Quantification of Emesis (PUQE) score: mild (≤6), moderate (7-12), severe (≥13) 1
• Early treatment may reduce progression to hyperemesis gravidarum 1

Management Approach for NVP

• First-line: Diet and lifestyle modifications including small, frequent, bland meals (BRAT diet: bananas, rice, applesauce, toast), high-protein and low-fat meals 1
• Avoid specific triggers such as foods with strong odors or certain activities 1
• Ginger (250 mg capsule 4 times daily) and vitamin B6 (pyridoxine 10-25 mg every 8 hours) are recommended by ACOG for persistent symptoms 1
• Doxylamine (H1-receptor antagonist) is FDA-approved for persistent NVP refractory to non-pharmacologic therapy 1
• Doxylamine/pyridoxine combinations (10 mg/10 mg or 20 mg/20 mg) are safe, well-tolerated first-line pharmacologic options 1
• Ondansetron, metoclopramide, promethazine, and IV glucocorticoids may be required in moderate to severe cases 1

Hyperemesis Gravidarum (HG)

Hyperemesis gravidarum is an intractable form of NVP affecting 0.3-2% of pregnancies, characterized by dehydration, weight loss >5% of pre-pregnancy weight, and electrolyte imbalances. 1

Clinical Course and Impact

• HG usually starts before week 22 of gestation 1
• Symptoms resolve by week 16 in >50% of affected persons and by week 20 in 80%, but persist throughout pregnancy in 10% 1
• HG can affect embryonic growth through maternal dehydration, electrolyte imbalances, and nutritional deficiencies that compromise fetal development 1
• Severe cases require IV hydration and adequate nutrition to prevent complications 1

Complications to Embryonic Growth

• Maternal malnutrition from HG can impair fetal development, particularly during critical periods of organogenesis in the first trimester 1
• Dehydration reduces uteroplacental blood flow, potentially affecting oxygen and nutrient delivery to the developing embryo 1
• Electrolyte imbalances can affect maternal physiologic support of the pregnancy 1

Other Common Symptoms

• Heartburn affects 30-90% of pregnant women, common in latter pregnancy and resolves after delivery 1
• Heartburn results from progesterone-induced relaxation of the lower esophageal sphincter, facilitating gastroesophageal reflux 1
• Abdominal attacks occur more frequently during pregnancy in women with certain conditions 1

---

C. Classic Physical Signs of Pregnancy

Hegar's Sign

Hegar's sign is softening of the lower uterine segment (isthmus) detected on bimanual examination, typically present at 6-12 weeks gestation. 7, 6

• This sign results from increased vascularity and hormonal effects on uterine tissue 7
• The softening creates a compressible area between the firm cervix and uterine fundus on bimanual palpation 6
• Hegar's sign is one of the probable signs of pregnancy used in clinical assessment before ultrasound confirmation 7

Goodell's Sign

Goodell's sign is softening of the cervix, similar in consistency to the lips rather than the nose, occurring early in pregnancy. 7, 6

• Cervical softening results from increased vascularity and hormonal effects (primarily estrogen and progesterone) on cervical tissue 7
• This change is detectable on pelvic examination and represents one of the earliest physical signs of pregnancy 6
• The softened cervix facilitates eventual cervical ripening and dilation during labor 7

Chadwick's Sign

Chadwick's sign is purplish-blue discoloration of the cervix, vagina, and vulva, resulting from increased vascularity and venous congestion in pelvic organs. 2

• This discoloration results from estrogen-induced vasodilation and increased vascular permeability 2
• The hyperestrogenic state causes increased blood flow to pelvic structures 2
• Chadwick's sign is typically visible at 6-8 weeks gestation and represents normal genital hyperpigmentation 2
• The sign is part of the broader pattern of hyperpigmentation affecting areolae, linea nigra, and genital tissues due to estrogen stimulation of melanocytes 2

---

Impact on Daily Routine and Occupational Considerations at 6 Weeks Gestation

Work Capacity and Modifications

At 6 weeks gestation, most women can continue normal work activities with modifications for symptom management, though NVP may significantly impact daily functioning. 1

Symptom Management for Working Professionals

• NVP peaks at 8-12 weeks, so symptoms will likely worsen over the next 2-6 weeks before improving 1
• Frequent small meals and snacks should be available at work to manage nausea 1
• Identify and avoid workplace triggers such as strong odors, certain foods, or activities that exacerbate nausea 1
• Consider flexible work hours to accommodate morning sickness, which despite its name can occur throughout the day 1

Physical Work Considerations

• Heavy lifting (>10-20 kg or 22-44 lb) more than 20 times per week in early pregnancy is associated with increased risk of preeclampsia 1
• Prolonged standing and stooping increase intraabdominal pressure, hypothesized to increase risk of preterm delivery and spontaneous abortion 1
• Joint laxity presents early in pregnancy and persists beyond 6 weeks postpartum, reducing load-bearing capacity 1
• Pregnancy-related musculoskeletal problems arise from reduced load-bearing capacity associated with joint laxity and increased abdominal mass 1

Cardiovascular Considerations

• Avoid supine positioning for prolonged periods as the enlarging uterus can compress the inferior vena cava even in early pregnancy 2
• Left lateral positioning optimizes cardiac output by relieving vena caval compression 2
• Venous insufficiency may be exacerbated by constrained postural demands such as prolonged standing 1

Common Pitfalls and Caveats

• Do not dismiss severe or persistent vomiting as "normal morning sickness" - early recognition and treatment of NVP may prevent progression to hyperemesis gravidarum 1
• Physiological changes should not be overestimated as pathology might be missed - maintain appropriate clinical suspicion for true pathology 1
• Respiratory rate is unchanged in pregnancy - if >20 breaths per minute, consider pathological causes 1
• Temperature and oxygen saturation are unchanged throughout normal pregnancy 1
• The severity of NVP in this pregnancy cannot predict symptoms in future pregnancies 1
• Low back pain and pelvic girdle pain are common (up to two-thirds experience LBP, nearly 20% experience PGP) but often underreported to prenatal providers 1