Hsu explains that people are at their physical peak at 25-35, and then they start to go gradually downhill. Their metabolisms also worsen. Becoming pregnant may naturally trigger high blood pressure, diabetes and other chronic conditions. What's more, in older pregnant women the cardio-respiratory and endocrine systems function worse than in younger women, so the former tend to have higher rates of breathing difficulties, including hyperventilation.
徐振傑解釋，人類的身體機能約在 25 ~ 35 歲到達高峰，之後就漸走下坡，新陳代謝也變差，懷孕過程自然容易引發高血壓、糖尿病等疾病；加上高齡婦女的心肺功能、內分泌協調能力均不如年輕人，懷孕時出現「換氣不足」、呼吸困難的比例也較高。