Because the capacity of the womb and that of the mother to supply nourishment are limited, there can be competition between the twins while still in the womb.
嫁給雙胞胎的陳如屏自己也生了孿生兄弟，她表示，要特別注意雙胞胎肺部感染的毛病，儘量保持室內空氣的新鮮和暢通，而且要預防感冒的併發症。此外，孕婦子宮的空間和身體所能供給的養分都有限，因此孿生子在媽媽的肚子裡就有競爭，難免有勝負。