Using ocp lo lo (10mcg estradiol, 1mg norethidrone acetate) for 3 months. have noticed by pill 7 the cervix starts to dilate. no spotting/period, why?

Lo Loestrin : Lo Loestrin is a very low dose pill, i.e. It had very little estrogen, so it stimulates very little growth of the uterine lining. This means there is very little to bleed off at the time of your period. It is normal to only have a little light spotting or skip periods on Lo Loestrin. This is not a problem since the progestin is what provides contraception. The estrogen just regulates periods.