The three trimesters of pregnancy, week by week
First, second, third — when each trimester starts, what weeks it covers, and how the pregnancy timeline is divided.
trimesters of pregnancyArticles on pregnancy dating
Plain-language explanations of how due dates and gestational age are calculated — the methods behind the wheel, how accurate they are, and the terminology you’ll meet along the way. Every article is reviewed against ACOG and NHS guidance and carries the same medical disclaimer.
Pregnancy weeks to months: the complete conversion guide
Why 40 weeks is nine months, not ten — and a full chart converting every pregnancy week to its month and trimester.
pregnancy weeks to monthsHow many weeks and days are you pregnant for?
Forty weeks, 280 days, nine-ish months — why pregnancy is counted the way it is, and how to find exactly where you are.
how many days are you pregnant forGravida, para and TPAL: what G3P2002 actually means
That string of letters and numbers on your chart has a simple logic. What gravida, para and TPAL mean, with worked examples.
gravida para meaningHow to use the OB wheel calculator: every mode explained
Which mode should you pick, what do you type, and how do you read the result? A plain walkthrough of all six calculator modes.
how to use an ob wheelHow far along am I — and when can you find out the sex?
Find out how many weeks and days along you are from any dating method — and roughly when a scan can reveal the sex.
how far along to find out genderOvulation and dating a new pregnancy after miscarriage
Ovulation can return within weeks of a loss, and dating a new pregnancy takes a little more care. A gentle, evidence-based guide.
ovulation after miscarriage calculatorMenstrual cycle length and how it changes your due date
A longer or shorter cycle moves your ovulation day — and your due date with it. How to measure cycle length and why it matters.
menstrual cycle length calculatorOvulation timing and signs: when it happens and how long it lasts
When ovulation happens, how long the twinge lasts, and how the fertile window really works — the timing behind conception dating.
how long does ovulation pain lasthCG levels and doubling time in early pregnancy
Early on, hCG roughly doubles every two to three days. What the doubling-time number means — and why a single reading tells you little.
hcg calculator doublingIUI due date calculation: dating a pregnancy after insemination
Intrauterine insemination lines up with ovulation, so dating is nearly as clean as IVF — about 266 days from the procedure.
iui due date calculatorAstrology pregnancy “calculators”: what the evidence says
Popular, fun, and not a dating method. A respectful, evidence-based look at astrology-based pregnancy and gender predictors.
astrology pregnancy calculatorPregnancy calculators in other languages: does the maths change?
Malayalam, Hindi, English — the dating maths is identical everywhere. What actually differs is terminology and interface.
pregnancy calculator malayalamOB wheel app vs. online calculator: which should you use?
Download an app, or just open a web page? A practical comparison of speed, privacy, and accuracy for pregnancy dating.
ob wheel appPregnancy trimesters and key milestones, week by week
A clean map of the pregnancy timeline — trimester boundaries, viability at 24 weeks, and what “term” really means.
pregnancy trimesters and milestonesPeriod of gestation (POG): what it means and how to calculate it
“POG” on a chart just means how far along the pregnancy is. What the term means, how it's written, and how to work it out.
pog calculator appConception date and due date: what you can and can't know
If you know the day you conceived, the due date is 266 days later. But how well can anyone actually know that day?
conception date calculatorIVF due date calculation: day-3 vs day-5 transfers
IVF dating is the most precise there is, because the timing is known to the day. How transfers and retrieval convert to a due date.
ivf due date calculatorHow accurate is your due date, really?
Few babies arrive on the exact date. What the estimate really means, why methods disagree, and when the scan should win.
due date accuracyGestational age vs. fetal age: what's the difference?
Why “how many weeks pregnant” is counted from your last period, not from conception — and the two-week gap that confuses everyone.
gestational age vs fetal ageCrown-rump length (CRL) and first-trimester ultrasound dating
Why the first-trimester scan is the gold standard for dating, how crown-rump length becomes a due date, and when it overrides the last period.
crown rump length calculatorNaegele's rule: calculating a due date from your last period
The 280-day rule behind every pregnancy wheel — where it comes from, how cycle length changes it, and when to trust a scan instead.
ob wheel pregnancyHow to read a pregnancy wheel (the circle chart), step by step
Line up one date, read off the rest. A plain-language walkthrough of the pregnancy circle chart and the mistakes to avoid.
pregnancy circle chartWhat is an OB wheel, and how do clinicians use it?
The pregnancy dating wheel that clinicians spin between patients — what it is, how it works, and what an online version does better.
ob wheel