Advanced age is the most important modifiable risk factor for women with infertility. Other risk factors include diabetes mellitus, hypothyroidism, PCOS etc.
Obesity is linked to infertility via various pathways, including peripheral aromatisation of estrogens leading to increased testosterone production which decreases gonadotropin secretion.[4]
Being underweight also causes infertility as evidenced by the female athlete triad. Low body weight is linked to infertility and sub fertility due to functional hypothalamic amenorrhea.
Hormonal imbalance can cause infertility. The most common cause of hormonal imbalance is PCOS.
Environmental hazards such as smoking, alcohol abuse, drug abuse etc.