At 13‑17 weeks gestation I experience nightly pain lasting about 30 minutes; what is the likely cause and appropriate management?

Nightly Pain at 13-17 Weeks Gestation: Likely Causes and Management

The most likely cause of nightly pain lasting 30 minutes at 13-17 weeks gestation is musculoskeletal pain related to pregnancy-induced anatomical and hormonal changes, and acetaminophen is the recommended first-line treatment when non-pharmacological measures are insufficient. 1, 2

Understanding the Pain Pattern

Physiological Changes at This Gestational Age

At 13-17 weeks gestation, your body undergoes significant musculoskeletal adaptations that commonly cause pain:

• Hormonal effects: Progesterone causes ligamentous laxity throughout the pelvis and spine, leading to joint instability and muscular strain 3, 4
• Postural changes: Even in early second trimester, the growing uterus begins shifting your center of gravity forward, causing compensatory lumbar hyperlordosis and anterior pelvic tilting 4, 5
• Timing pattern: The nightly occurrence and 30-minute duration suggest musculoskeletal pain that accumulates throughout the day and manifests when you rest, which is characteristic of pregnancy-related low back or pelvic girdle pain 6

Most Common Pain Locations

• Low back pain affects approximately 45-50% of pregnant women and frequently begins in the second trimester (which includes your 13-17 week timeframe) 7, 6
• Pelvic girdle pain can present as early as the first trimester but commonly intensifies in the second trimester 4

Differential Considerations

While musculoskeletal pain is most likely, you should be evaluated if the pain has any of these features:

• Severe, unrelenting pain that doesn't improve with position changes or rest (could indicate placental abruption, though this is rare at this gestational age and typically presents with bleeding) 8
• Fever, dysuria, or flank pain (suggests urinary tract infection or pyelonephritis) 8
• Right lower quadrant localization with fever (appendicitis, which can occur at any gestational age) 8
• Cramping with vaginal bleeding (threatened miscarriage, though less common after 13 weeks) 8

Management Algorithm

First-Line: Non-Pharmacological Approaches

Start with these evidence-based interventions before considering medication:

• Ice packs or heating pads applied to the painful area for 15-20 minutes 2, 9
• Rest periods throughout the day to prevent pain accumulation 3
• Positional modifications: Avoid prolonged standing (which worsens pain in 27.2% of pregnant women) and use side-lying positions with pillow support between knees at night 6
• Gentle exercise and stretching: Physical therapy-based exercises are safe and effective for pregnancy-related musculoskeletal pain 3, 7

Second-Line: Pharmacological Treatment

If non-pharmacological measures are insufficient after 3-5 days:

• Acetaminophen (paracetamol) is the only recommended medication at your gestational age 1, 2
  • Dosing: 650 mg every 6 hours or 975 mg every 8 hours, not exceeding 4 grams daily 1, 2
  • Duration: Use the lowest effective dose for the shortest duration, ideally ≤7 days 1, 9
  • Safety consideration: While acetaminophen remains the safest option, emerging evidence suggests prolonged use (>28 days) or second-trimester exposure may be associated with a 20-30% increased risk of neurodevelopmental outcomes in offspring, so minimize duration when possible 1, 9

What to Avoid at 13-17 Weeks

• NSAIDs (ibuprofen, naproxen): While some guidelines permit cautious use during the second trimester (weeks 14-27), they should only be considered if absolutely necessary and for very short durations (7-10 days maximum), as they carry risks even before the strict contraindication at 28 weeks 1, 2
• Opioids: Should be avoided unless pain is severe and unresponsive to acetaminophen, and only at the lowest dose for the shortest duration 2
• Gabapentin, pregabalin, tricyclic antidepressants: All lack safety data in pregnancy and should not be used 9

When to Seek Urgent Evaluation

Contact your obstetrician immediately if you experience:

• Pain that is severe, constant, or progressively worsening 2
• Any vaginal bleeding accompanying the pain 8
• Fever, chills, or signs of infection 8
• Pain localized to the right lower abdomen with nausea/vomiting 8
• Pain that interferes with daily activities despite treatment 3

Expected Course

• Most pregnancy-related musculoskeletal pain improves with conservative management 3, 5
• Pain patterns may change as pregnancy progresses, with many women experiencing peak symptoms in the second trimester (which you're currently in) 6
• Symptoms typically resolve postpartum, though this may take several weeks to months 5