It sounds like a twist in a TV soap. The gynaecologist tells the woman that she is six weeks pregnant, and the husband knows he was at a conference then. Has she been unfaithful?
It turns out you can actually be "six weeks pregnant" even though you didn't have sex six weeks ago.
This occurrence has been explained by Midwife Marley, an author, midwife and expert on pregnancy and gestation.
In a video posted to her 160,000 followers, Marley explained why the conception date and gestation often don't match
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"Health care providers measure pregnancies in weeks starting from the first day of the last menstrual period," she says. For someone who has an average 28-day cycle, ovulation generally happens around day 14 of their cycle, then conception probably took place about two weeks after their last period. For gestational age counting, these extra two weeks are added to a pregnancy as a simple method."
In short, there are usually two weeks added to your pregnancy date.
Marley explained that a woman had contacted her in distress, as her gestation period didn't match up to the time she had sex, and her husband was starting to have doubts over his paternity. Marley made the video to reassure women in this situation why this discrepancy occurs.
She also added that it's important "to note that although worldwide average pregnancy is 40 weeks, there are many variations depending on health, height, weight and ethnicity. This is why some women will carry their babies until 42 weeks, and others until 38."
Marley's followers thanked her for clearing up something that can cause couples a lot of needless distress
"I think there needs for better awareness of this," said one. "I had an early scan and the clinic tried to tell me I conceived earlier than I thought. It made for an awkward appointment."
"Thank you for this," wrote another. "I'm almost 100% positive I know when I conceived, but all the due date predictions are two weeks different. This helps explain why."
To learn more about pregnancy, visit the HSE website here