Rigid plans work best if you're building a skyscraper; with something as mysteriously human as giving birth, it's best, both literally and figuratively, to keep your knees bent.

The line contrasts the engineered certainty of construction (“building a skyscraper”) with the unpredictability and embodied reality of childbirth. “Rigid plans” stand for over-control and inflexibility; the speaker argues that birth—“mysteriously human”—requires adaptability, humility, and responsiveness to changing conditions. The advice to “keep your knees bent” works on two levels: literally, it evokes a physical posture associated with readiness, grounding, and allowing the body to move; figuratively, it suggests staying flexible, not locking into a single script, and being prepared to adjust expectations. The quote ultimately endorses openness and resilience over perfectionism in intimate, high-stakes life events.