Am I the Baby's Dad? -- SW writes

Stinkywink writes on the bottom of one of the longer threads, the following:  "My gf says she is 5wks preg however I only slept with her for the first time 3wks 4 days ago?? Is this possible???"

Stinky, here is what you need to know to understand how doctors time pregnancy.

Back in Grandma's day (and for generations before that), the only way a doctor had to tell when a pregnancy began was by starting the count with a big signal.  No ultrasounds were available, and not even any pregnancy tests (by my mom's day they used one that would actually kill a rabbit, but nothing like we have now).  So the only way to start the clock for the purposes of knowing how far along a baby was progressing was to begin counting on Day 1 of the woman's last period, before she got pregnant and stopped having periods.  No doctor thought a woman was in fact pregnant when she was having her period, but that was a good place to begin counting.  (Ovulation is hidden and still mysterious in its timing.  Blood, you can see.)  That counting method has persisted until now.  Day 1 of "pregnancy" is day 1 of bleeding of the period.  That happens for about five days, and in another seven or so days after that, ovulation occurs.  A full term-pregnancy from conception to birth is 266 days, but doctors back it up by adding another 14 days at the front, making the "40 week" pregnancy 280 days long.  When the doc told your girlfriend she was 5 weeks pregnant, he was saying the same thing as if he said "The first day of your last period was 5 weeks ago and you conceived around 3 weeks ago."

So, you're gonna be a daddy.  

If this is not a clear explanation (and I'm first to concede that it seems to have been made pretty obsolete as a pregnancy counting method because of modern test availability), go with her to her next appointment, and ask the doc to explain the difference between the presumed date of conception, and the 'gestational age' of the pregnancy.  (The latter being, the way the doctors count it, starting with the first day of the last period.)