O-3, O-2, O-1 vs. O day... Does it matter?

[savedandsanctified]

This might be the dumbest question to ask, but we have only recently started trying and I always read of someone being upset for not BDing on O day. Does that really matter? Is it not safe enough if you have hit the days before (or at least some of them)? Please correct me if I am wrong, I am genuinely trying to figure out how to go about this without too much stress.

 

[mcg1102]

@savedandsanctified Based on the data, what comes out is the following hand-wavy ranking system:

Top: O-2, O-3, O-1 (~equal, O-2 being perhaps slightly better) (20-30% chance)

Middle: O-4, O (10-12% chance)

Low: O-6, O-5, O+1 (0-5% chance)

Note that these are all single-day probabilities — the odds of getting pregnant if you have sex only on one day of the fertile window. Having sex on multiple days of the fertile window helps a little, but not a ton. The maximum odds per cycle aren’t much higher than about 30%.

For less hand-waving and more data, see some studies that investigate this:

1. Wilcox NEJM 1995. The best days from this study are O (32.5%) and O-1 (30%).
2. Wilcox Human Reprod 1998. A study by the same authors as the first. They find that, while the pregnancy rate is higher with O-day sex, the early miscarriage rate is also higher. The best days from this study are O-2 (30%) and O-1 (27.5%).
3. Colombo Demo Res 2000. A large multicenter European study. The best days from this study are O-3 (27%) and O-2 (24%).

 

[katrina2017]

@mcg1102 I had been feeling disheartened because DH and I only hit O-2 this cycle, but this comment helped a lot. So, thanks

 

[thisisaname]

@savedandsanctified I've always heard it's better to hit days before. It's best to already have swimmers up there when the egg is released.
I think the other one depends on fertile CM. If you have a ton, a few days before should be fine because they can swim well. If not, maybe closer to O.

 

[indianwomenhealth]

@savedandsanctified So DevBio already said the technical accurate thing, but I wanted to add another angle to this.

For myself, being upset about not hitting O is not exactly about not hitting that exact day (especially as it is a lower chance), but that I want this so badly, that I want to give myself the very best chance and even though this may be wrong, it feels like "the best chance" is hitting every single one of O-4, O-3, O-2, O-1 and O. Covering all my bases, so to speak. There is SO LITTLE that I have control over in this dumb journey, but having sex on the most days possible is something I CAN control. But then life happens... and this cycle, even thought it was my goal to hit every day, we only got O-2 and O-1 so I'm a bit disappointed that we "didn't try hard enough". I know that is silly and I have read many sites say it actually might be better NOT to have sex every single day, and most places say you really are fine doing EOD, but still. It's a mental block for me. And it gives me something to blame myself for if we aren't pregnant (that we didn't BD enough) and also gives me something to shoot at improving next cycle (BDing more). It's not MUCH but at least it's a very little something I actually have agency in changing.

 

[mcg1102]

@indianwomenhealth So I definitely have to be clear that this is a "do as I say, not as I do" situation -- rationally, I know the stats, but I also get a little too goal-oriented when it comes to fertile window sex.

But given that I'm a hypocrite, remember to be kind to yourself. Please don't be disappointed if you miss a day -- it's important to live your life, too, not just to be a Fertile Window Sex Robot. But I do understand the feelings.

 

[growingrace]

@savedandsanctified I think it's better to hit the days prior, probably O -1 being best.

 

[steveinalberta]

@savedandsanctified It's a great question