Lesson 6 · Pregnancy & Parenthood
Twenty minutes that replace every date you currently hold. There is one way to get this appointment wrong, it happens at the booking desk, and it is the only thing in this lesson you have to act on.
Pud Pud is 4+6 today. The scan is the next real event after booking, and it does four jobs at once: sets the official due date, counts the babies, checks the pregnancy is viable, and — if you want it — takes the neck-fold measurement that the combined screening test is built on.
The antenatal timeline I gave you said the dating scan window was 11–25 October. That is the window for a scan, but it is not the window for the screening test, and if you book inside it you can lose the test. Corrected, and worth understanding rather than memorising.
The combined test needs the baby measured at a crown–rump length of 45.0 mm to 84.0 mm — head to bottom, the only length worth measuring in something with its legs curled up. That range is what defines the window, not the calendar: 45 mm is about 11 weeks 2 days and 84 mm is 14 weeks 1 day.¹ Too small and the neck fold can't be measured reliably; too big and the anatomy has moved on.
| Gestation | Your date | What it means |
|---|---|---|
| 10+0 | 11 Oct 2026 | Earliest a dating scan is offered. Too early for the neck fold. |
| 11+2 | 20 Oct 2026 | Baby hits 45 mm. Combined screening becomes possible. |
| 12+0 | 25 Oct 2026 | The usual "12-week scan" date. Comfortably inside the window. |
| 14+1 | 9 Nov 2026 | 84 mm. The door shuts. Nothing reopens it. |
When the scan appointment is offered — at booking, or by letter — check the date is on or after 20 October. If they offer the 14th or the 16th, say: "we want the combined screening — can we have a date after 11 weeks 2 days?" Sonography clinics book to their own capacity, not to your screening window, and nobody at the desk is checking this for you.
If you miss it — scan too early, baby lying wrong, or the measurement can't be got — the fallback is the quadruple test: a blood test only, offered between 14+2 and 20+0 (10 Nov – 20 Dec for you). It screens for Down's syndrome and, since 2024, Edwards' — but not Patau's, and it is less accurate than the combined test.¹ A fallback, not an equivalent.
Cold gel, a probe on her belly, a screen she can see and you probably can't. She may be asked to come with a full bladder — it lifts the uterus into view.² Four things get done:
The sonographer will go quiet. This is concentration, not bad news — they are taking measurements to a fraction of a millimetre while the baby moves. Do not ask "is everything okay?" mid-measurement; ask at the end, when they will tell you properly.
9 May 2027 is arithmetic, not evidence. It assumes a 28-day cycle and ovulation on day 14. The scan measures the actual baby, and the scan's answer replaces the calculated one. A shift of a few days either way is completely ordinary.
What matters is that a surprising number of things are pinned to that date, so if it moves, they all move together:
| Pinned to the EDD | On 9 May 2027 |
|---|---|
| Qualifying week (15th week before) | 24–30 Jan 2027 — the SMP eligibility test |
| MATB1 issued (from 20 weeks) | 20 Dec 2026 |
| Earliest maternity leave (11 weeks before) | 21 Feb 2027 |
| Anomaly scan (18–20+6 weeks) | ~6–26 Dec 2026 |
| Days between the birth and her contract ending | 19 — and 28 May is fixed |
Her Herman Miller contract ends 28 May 2027 whatever the scan says. If the scan moves the due date later, the gap between birth and contract end shrinks — a nine-day move leaves ten days, and the whole handover-and-leave sequence compresses. If it moves earlier, you gain room. Text me the scan EDD the same day and I'll recompute every date in Money & Dates. Do not carry on quoting 9 May once you have a real number.
You have been living with an unspoken risk since August. Here it is with numbers on it. Roughly 1 in 5 confirmed pregnancies ends in miscarriage, overwhelmingly early. But once a heartbeat is seen on a scan, the picture changes fast: at 6–7 weeks the chance of ongoing loss is around 10%; at 8 weeks the pregnancy continues in about 98% of cases; by 10 weeks, 99.4%. Second-trimester loss runs at 3–4%.⁴
That is why people tell the world at twelve weeks. It isn't superstition, it's the curve. It is also why this scan carries the weight it does — for most couples it is the appointment where the pregnancy stops being provisional.
So have the conversation before the scan, not in the car park after: who do you tell, when, and who tells them? Two things worth naming. Her employer has a legal deadline — she must give notice of the pregnancy by the end of the qualifying week, 30 January 2027 — so there is no rush from that direction. And if you tell nobody and something goes wrong, you grieve alone; some couples deliberately tell two or three people early for exactly that reason. There is no correct answer here, only a decided one.
The clinic offers you a dating scan on 15 October. What do you say?
15 October is 10+4 — the baby is under 45 mm and the neck fold cannot be measured, so combined screening is lost. The window opens at 11+2, which is 20 October, and closes at 14+1 on 9 November. Nobody at the booking desk checks this.
What measurement actually sets the due date at this scan?
Crown–rump length, 45–84 mm. Nuchal translucency is the neck fluid, and it is for screening, not dating. Head circumference dates later pregnancies — it's what the quadruple test pathway uses after 14 weeks.
The scan puts the due date at 14 May, not 9 May. What follows?
Scan dating replaces LMP dating. The qualifying week, MATB1 date, earliest-leave date and anomaly scan all shift with it — while her contract still ends 28 May 2027, so the gap between birth and contract end drops from 19 days to 14.
The neck-fold measurement can't be obtained on the day. What is offered instead?
The quadruple test — blood only, 14+2 to 20+0, which for you is 10 November to 20 December. It covers Down's and Edwards' but not Patau's, and is less accurate. NIPT and amniocentesis come after a higher-chance result, not instead of screening.
Spacing check, from Lesson 5: how much dividend headroom before 5 April 2027?
The band runs to £50,270 and dividends above it jump from 10.75% to 35.75%. Your 2026/27 income is already ~£34,000 (£10k PAYE plus dividends since), so roughly £16,000 of room is left this tax year. Draw into it before 5 April; hold the rest as retained profit in TWP at 19% and take it against a fresh allowance in 2027/28.
Free recall: the two dates that bound the combined screening window, what makes them those dates, and the three questions you ask before leaving the room.