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Newbie with a delicate question

Hello, never been here before but I'm looking for some advice/clarification if possible.

I'm a 29 year old male and had a fling with a woman relatively recently that was all very casual. In the past two weeks she has told me she's pregnant and that she has only been with me.

She went to the doctors on Monday 25th July where they told her she was anywhere between 2-4 months pregnant. She went for a scan yesterday (Friday 29th July) and we were able to meet afterwards. She told me that at the scan they had told her she was 8 weeks and three days pregnant and that the estimated due date was February 16th 2017.

At took this at face value until my sister noted that these dates don't match up. We checked them and realised that if she was 8 weeks three days pregnant the EDD would be at least a couple of weeks later.

We slept together 23rd May and then again on 30th June.

I'm in way over my head so I have no idea if these dates could still work, if she's lying to me or if she's simply made a mistake.

Any advice/help would be greatly appreciated!

Thanks in advance

17 Replies

if she is 8 weeks four days today? her due date would be 4th march, im 15 weeks + 1 day and due 20th Jan, she would be due 6 weeks 4 days after me, doesn't mean to say she is lying maybe got dates mixed up, maybe you could attend a scan or midwife appointment with her, she should have another scan at roughly 12 weeks, good luck


also the dates you had sex does not match with her dates of conception, they add two weeks on top of the day conceived, so realistically say she conceived on the 30th the last time you had sex she would now be 6 weeks +2 , I hope this helps


The dates don't match the dates you slept together. The date in May was too early if she was 8w+3 yesterday and the date in June was too late. Something doesn't add up here!


Because pregnancy is measured from when the body prepares itself to become pregnant rather than when the egg was fertilised the date of conception (ie when you slept together) should be 2 weeks (ish) into the pregnancy. I know that sounds a little weird but every month the female body prepares itself to get pregnant and this is included in the how many weeks pregnant you are and is why they calculate from last period and not when you had sex. There will also be a little variation as every baby grows at a different rate so dates could really be adjusted a week either way on scan. I hope that helps although I can understand your stress.


Sperm can survive inside a woman's body for up to a week. So even if she ovulated after you had sex then the baby would still be yours. You could have conceived in May.

I can understand your distress at the situation given that you weren't in a serious relationship but can you not also see it from her point of view. I doubt she is in any way trying to trick you and if she saying its your baby then in all likely hood it is. I'm sure she is upset and anxious too and if you're the father then you are in it together and should try and support one another the best you can.

By my calculations on Friday she would have been 10 weeks and 1 day however this doesn't mean she is lying to you. Would it be possible for you to attend the next appointment together? For both of your benefit?

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The date doesn't seem to add up. If she had calculated it herself from the first date you both slept together, she would have had to tell you 9 months and 3 days. But that would not have been correct anyway as the pregnancy gets calculated from the beginning of your last period. It is true that cycle lengths can vary and that ovulation (the release of the egg, only after which it can be fertilized by sperm) can occur at different moments in the cycle than the expected midway point, which for most women is around the 14th day of a average 28 day monthly cycle. But if she had become pregnant in the cycle she was in when you slept togehter on 23rd may, she would have had to have been in that cycle for a few days at least, so she would be at least 10 weeks pregnant now.

The date would make sense if you took 23rd of may or the days thereafter (the sperm can survive in the vagina for a number of days and wait for the egg to be released) as moment of fertilization and calculated implantation, which occurs in the days thereafter, as the beginning of the pregnancy for 30 may. The doctors I know calculate the pregnancy from the first day of your last period though, that is the beginning of the growth process for the egg to be released.

Which country are you in? I ask this because whilst a woman herself is not unlikely to get mixed up and confused over the dates and the correct calculation herself, in the exitement of it all, doctors where I am tend not have this problem. But I wouldn't be able to say how doctors calculate pregnancy dates in other areas in the world.

There are the rare but sad cases where women invent a pregnancy for reasons that I can only imagine are psychological. The long term girlfriend of a guy I know pretended to be pregnant, to him, to his mother, their friends, everyone. He got worried when she didn't take him to any doctor's appointments. He found out in a very ardious process that she had never seen a doctor about it, the scans she had shown him were stolen god-knows-where and that the whole pregnancy was simply made up.

I am not saying this to scare you, just to be aware that sometimes very strange things can take place, so it's important not to ignore warning signs that tell you something might be wrong about the whole situation. If you ask she take you with her to a scan, and she agrees, that would be a very good sign. Then, at the scan, you can yourself ask the doctor what the actual stage of the pregnancy is. If she is happy to have that clarified with the doctor in front of you, again that would be a good sign.

If she doesn't let you take part in doctor's visits and if by her behavior you feel she is not telling you the truth about this, you can let her know in a very calm and non threatening way, after she is over 3 months pregnant, that you wish for a patenity test once the child is born. I say to wait for 3 months to be officially over because you wouldn't want her to ger very upset by your mistrust in a stage where a miscarriage is not uncommon to happen. Then you might feel guilty that you had caused the loss of the baby by upsetting her, a notion most probably misguided, but nevertheless you might feel that way. Or she might blame you, also not good.

Sorry it's become a long spaghetti answer - hope it helps. Good luck.

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As people said earlier the dates don't quite match but 1. ultrasounds is not 100% dates can be off by a week or two easily. 2. Depends what her period cycle is like all these dates would normally be calculated on 28days.

In my humble opinion... If you're not sure but want to be involved (just in case baby is yours) try attend scans etc with her but ask for Dna test straight away before baby is born.. so there's no doubts then and you won't miss out but also you'll know before you get too attached.


Hiya, you are right that all of the dates don't match up together, but some of them do, and the others could just be medical adjustments based on the scan.

If you slept together on May 23rd she could have ovulated already, or be preparing to ovulate, and realistically conception could have occured any time from May 23rd - May 30th.

If this is the case then a Feb 16th due date is perfectly reasonable.

Check out something like this due date calculator:

Conception on May 26th gives a due date of Feb 16th.

Note that they measure "weeks pregnant" and "fetal age" differently (by about two weeks).

As some previous answers said - pregnancy is measured from date of last period, not from date of conception, which adds two weeks on and is a little confusing. This calculator gives a fetal age of 9 weeks and she was told 8 - this could be something that is readjusted during a scan, based on the baby's development - I don't know if they do that.

I really understand your concern here, and you have an absolute right to know for sure that this is yours. But I think you will do yourself a really big favour if you tread very carefully here - it is certainly very possible that she is being completely truthful and this is your baby. Conception and due dates do match up. It is only "weeks pregnant" that doesnt, and there could be a development-based reason for that.

In that situation the last thing either of you need is a breakdown of trust or respect between you. I think suggestions in earlier answers to go along to the scans yourself (and not asking really obviously distrustful questions in front of her,...maybe ask the doctor when you are alone) is the best plan of action.

Good luck to you either way :) And just remember - there is never a "right" time to have a baby - and most people feel like they are totally not ready.

The way you phrased and asked your question sounds to me like you're a nice guy and not by nature distrustful. This is a good start :) and I really hope it all goes well for you either way. I think you're right to be looking for confirmation/clarification, and really really hope and advise that you get it without confronting her (ask the doctors in confidentiality) because if she is being truthful and you question her that will be a massive strain on your friendship/relationship - she's likely going through all the same internal freaking out. (I'm 6 weeks pregnant myself, and it's a rollercoaster!)

All the luck in the world to you


A doctor will not discuss someone else's case alone with a third party. there's a thing called confidentiality.


What purpose does your sarcasm serve apart from to make people feel bad? If she says he is the father then she has made it his case too. They are equal parents. A doctor won't discuss her medical details but will discuss the pregnancy - it is also his pregnancy case since the minute she said it was. There is also such a thing as fathers. Just trying to help the guy out.


I'm not sarcastic. The doctor can't discuss her pregnancy (aka her medical details) without her consent. No sarcasm at all. And a doctor can't tell who the father within a 2 week period is only a DNa test can.


Dating on an early scan can also be off as what they are measuring is so small. For example I was dated a week behind on an early scan, you get a better idea of dating from 12 weeks. Ultimately the only way you are going to know for sure is a DNA test.

But it does all seem a bit vague, for example the whole thing of doctor saying she was 2-4 months, they would have given her an estimated date based on date of last period.

Proceed with caution, you've had some great advice above and good luck.


The confusion may be due to how doctors describe the length of pregnancy. For the first two weeks of pregnancy, the woman isn't actually pregnant (yes, I know that sounds crazy - bear with me!). This is because a woman usually ovulates 2 weeks after her period, which is the 24-hour window when she's actually fertile. However, this can vary, so women often can't be 100% sure of the conception date, but they should know when their last period was. Hence, doctors count a pregnancy from the date of the last period. For example, I'm 38 weeks pregnant, but actually conceived at around the 2-week mark.

So if the baby is yours, her pregnancy (and hence calculation of the due date) began either on 23 May minus two weeks, or 30 June minus two weeks.

If there is any discrepancy between dates of the last period and how far along the pregnancy appears to be on the first scan, doctors will go with the scan, as it's a more accurate indication; however, they'll continue to add the standard 2 pre-pregnant weeks to the overall total of how many weeks pregnant a woman is.


A couple of people have suggested that conception would have to be on either of the two dates you were together. That is NOT the case. Sperm can survive up to a week in the uterus so conception could be anytime for a week after you had sex if she was only ovulating on that day.

Just so you know and don't base your conclusions on wrong info!

These dates COULD work, with a leaway for error of one week regarding the scans (see my earlier message)

Best of luck


In the words of Chris Brown, "these hoes ain't loyal". Good luck, you sound like a decent chap. Get that DNA test asap to avoid a lifetime of wondering.


Thanks for all the info and comments everyone!

I will definitely see if I can attend the next scan, I don't think this should be a problem.

Much appreciated!


I have had 4 kids and the first three have all been overdue by 1 week plus, 2 weeks and 3 weeks plus, last one was induced as that pattern was clearly repeating itself and was having Spd. Due dates are estimated and not exact. Sperm also survives longer and lots of people conceive later than calculated. What am saying is that if you slept with her and had unprotected sex then she could be telling the truth. If baby comes and you are still full of doubts and she has nothing to hide then a DNA test will be the answer. I am in a mixed race relationship as well, some kids have come too dark and too light and all same Mum and Dad. Anything is possible, please keep an open mind and it is new to both of you. Wishing you the very best for the future.

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