WEEK 12Trimester 1•Baby: Lime / Plum
End of First Trimester & Reflex Architecture
Estimated Length5.4 cm
Estimated Weight14 g
Fetal Morphogenesis & Anatomy Highlights
- •Fetal reflexes active: spontaneous curling of toes, opening/closing of mouth, swallowing amniotic fluid.
- •Intestinal loops return from physiological umbilical hernia into abdominal cavity.
- •Fetal kidneys produce functional urine, filtered into amniotic sac.
- •Cranial bones visible with prominent echogenic choroid plexuses in lateral ventricles ('butterfly sign').
Same-Day Assessment / Urgent Care
Week 12 Urgent Red Flags
Immediate clinical evaluation or presentation to Winnipeg Obstetric Triage (HSC / St. Boniface) is indicated if:
- •Nuchal translucency >= 3.5mm (warrants genetic counseling, diagnostic testing via CVS/amnio, and fetal echocardiogram)
- •Vaginal bleeding or sudden fluid gush
- •Persistent fever or chills
Women's Hospital HSC Triage: 204-787-8600 | St. Boniface: 204-237-2263
Clinician Perspective • Physiological & Screening Protocols
Maternal Physiological Adaptations
Fundus reaches superior border of pubic symphysis. Pelvic pressure on bladder temporarily decreases as uterus rises into abdomen.
Expected Clinical Symptoms
Gradual subsiding of severe nauseaShift from pelvic to abdominal uterine positionMild pelvic fullnessIncreased vaginal discharge (physiologic leukorrhea)
Clinical Investigations & Screening Schedule
- ✓Nuchal Translucency (NT) ultrasound (target window: CRL 45mm to 84mm; normal NT < 3.0mm).
- ✓First trimester serum markers: PAPP-A and free beta-hCG.
- ✓Uterine artery Doppler screening for preeclampsia risk assessment (if indicated by SOGC clinical risk algorithm).
Upcoming Visit Horizon: Routine 16-week prenatal follow-up.