In addition, serum NP content is positively correlated with estrogen levels, andnegatively correlated with progesterone level, confirming that NP plays the role ofestrogen by binding with various estrogen receptors, disrupting the body's normalendocrine function, leading to excessive estrogen secretion and to progesteronesecretion deficiency, and subsequently causing threatened abortion symptoms in pregnantrats. This evidence concerns the gene ESR1 and abortion.