Sort of protection

You nuzzle her, the massive mass of hair cutting off most vision and sound as your cock rubs against her pussy "you know there are other forms of protection, we could get you on pills or geta a diaphragm..." you push forward, feeling something inside of her give and she whimpers "or I could just pull out... or... how long ago did your last period end?" she gasps clawing at your back for support. You can see the wheels in her head turning as she tries to answer a question while getting her pussy penetrated for the first time, raw and unprotected. She breathes heavily as you keep moving, slowly but never quite stoping as you drill deeper and deeper into her "7 days, last Monday" you smiles "you aren't fertile until your 14th day to the 21st. if I keep from cumming in you on those days we should be safer" she brightens though looks a little disappointed "so I can't get pregnant today?" you chuckle and pat her head causing her to look ashamed of herself again but also causing her pussy to squeeze your cock "no, it is just safer. Any time you get cum in you it could be the time a swimmer finds your egg and puts a baby in you" she looks up at you nodding, clearly your explanation had turned her on a lot as before she was totally still except for the involuntary motions of her pussy but now she is bucking back up into you.