I think the internal scan gives a more accurate date has they get a closer look but i.could be wrong. The conception.date i think can be around a week. My best advise is to look online at a pregnancy due date calculator has they tell you when your possible conception.date will be. I know there is a few online or try typing in a pregnancy conception.calculator has that should help you.
Period dates would b a good base to go off! U generally ovulate 2 weeks b4 expected due period so if u have 28 day cycles 2weeks from 1st bleed day.
10 days apart is pretty close but think u could make a fair guess who's it was as the dating is so accurate and within a couple of days but as u say only dna is a definate.
Also when u miss ur period ur classed as 4 weeks pregnant and this is how docs, midwife, ultrasound tecs etc date u but actually the baby has only been there a max 2 weeks, more likely 10 days! Working on the law of averages.
Have u decided not to have an abortion or working out who's it is 1st b4 u decide?
By my working out 7weeks 6 days takes u to 19 dec for conception. And the 1st day of ur last period 5th Dec!
If ur dating at 6 weeks 4 days this would put conception 28th dec. And 1st day of last period 14 dec.
To b ur 1st partners u would date around 9 weeks 2 days . And put ur last period around 25th Nov.
This is working off the average 28 day cycle .
Also they believe sperm can live up to 7 days so would clear u 3 days if u got caught 19th spot on .
Some people ovulate sooner, some later its all averages but I would use the dating scan especially if u don't have regular periods.
Also male sperm swim quicker but don't live as long as female sperm who are slower swimmers, so could b there ready and waiting a few days b4 u actually ovulate for an egg to come to be fertilised.
the best advice i would give is use this link nhs.uk/conditions/pregnancy... its the NHS direct pregnancy due date calculator and it will give you an accurate result it did for myself hope this helps or if your still not sure make an appointment with your gp/nurse practitioner and express your concerns with them and they can calculate then
I had a scan at 7 weeks. The also had both types of scan and had varying dates. The ultrasound nurse told me to go with the oldest date as will be the baby at it's biggest- stretched out. When I got my 12 week dating ultrasound there was only a two day difference to the date they measured then so seemed right. I also had no idea of dates as irregular and unexpected. Obviously, none of that's set in stone. Particularly if you're basing a big decision on it. Hope you figure things out
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