Pregnancy Sickness
& The 4-Week Rule
Police Maternity Regulations • Automatic Leave Trigger • Equality Protection • Independent Explainer • Not Legal Advice
Snippet Target: Definition
What is the 4-Week Trigger Rule?
The 4-week trigger rule is a statutory mechanism in UK police regulations where maternity leave is automatically started if an officer is absent for a pregnancy-related illness during the four-week period leading up to their Expected Week of Childbirth (EWC). This overrides any planned later start date.
Source: Maternity and Parental Leave Regulations 1999 • Police Regulations 2003
Section 01
The 4-Week Rule Explained
In the police service, as with almost all UK employment, your maternity leave typically starts on the date you have notified your force. However, the law provides a 'safety valve' called the automatic trigger. If you are unwell and that illness is linked to your pregnancy, your force has a statutory obligation to move you onto maternity leave if you are close to your due date.
Key Rule: The Timing
The 4-week window refers to the 28 days immediately preceding the Sunday of your Expected Week of Childbirth (EWC). If you are absent for even a single shift due to pregnancy sickness on day 27 before EWC, the trigger activates.
The Mechanics of the Trigger
- Absence Identification: The absence must be classified as 'pregnancy-related' in your force's sickness management system.
- Day After Rule: Maternity leave starts from the day AFTER the first day of pregnancy-related absence within the window.
- Financial Pivot: From that moment, your pay shifts from sick pay (often 100% in police) to maternity pay (OMP/SMP).
Understanding your Expected Week of Childbirth (EWC) is the first step in auditing your force's actions. The EWC is not necessarily the same as your 'due date'. It is the week, starting on a Sunday and ending on a Saturday, in which your doctor or midwife expects your baby to be born, as recorded on your MATB1 form.
For example, if your baby is due on Wednesday the 14th of April, your EWC starts on Sunday the 11th of April. Your '4-week window' therefore begins four weeks before that Sunday. If you were to call into the control room or your sergeant and report sick due to morning sickness, exhaustion, or pregnancy-induced hypertension on any day within that 28-day lead-up, the regulatory 'clock' for your maternity leave starts ticking.
This is often a point of confusion for line managers who may mistakenly keep an officer on sick leave to 'help them out' so they don't 'waste' their maternity leave. While well-intentioned, this is actually a breach of the Maternity and Parental Leave Regulations. The trigger is automatic; neither the force nor the officer has the discretion to ignore it once a pregnancy-related absence has occurred within that window.
Section 02
Timeline Framework
| Stage | Sickness Status | Pay Type | Effect on Leave |
|---|---|---|---|
| Before 4-Week Window | Standard Sick | Standard Sick Pay (Reg 28) | None. Leave starts as planned. |
| Within 4-Week Window | Maternity Trigger | Switches to OMP / SMP | Leave starts day after absence. |
| Non-Pregnancy Sickness | Standard Sick | Sick Pay Remains | No trigger. Requires Med Evidence. |
| Premature Birth | Immediate Switch | Immediate MAT Pay | Leave starts day after birth. |
Reality Check: The Saturday Saturday Rule
Because the EWC always starts on a Sunday, the 'Trigger Window' effectively closes on the Saturday before your baby is due. If you report sick on the Sunday that starts your EWC, and you had intended to work until the following Friday, the trigger is already fully active. Your maternity leave will have technically started the day after your sickness, effectively ending your serving status for that period immediately.
Policy Variation Note
While the 4-week rule is a statutory baseline, some force policies may allow for 'Phased Returns' or 'Sickness Carry-over' in exceptional circumstances, but these never override the officer's right to maternity pay once the trigger is pulled. If in doubt, consult the Police Federation.
Section 03
Classification Criteria
Crucial to the 4-week rule is the classification of the sickness. Not all illnesses that occur during pregnancy are 'pregnancy-related' in a legal sense (e.g., a broken arm from a non-work incident). However, the courts have generally taken a wide view of what counts.
Hyperemesis Gravidarum
Severe nausea and vomiting that prevents duty.
Pregnancy-Induced Hypertension
High blood pressure requiring rest or monitoring.
Symphysis Pubis Dysfunction (SPD)
Pelvic girdle pain making movement or patrol difficult.
Gestational Fatigue
Profound exhaustion linked to the physiological demands of the final trimester.
Anxiety & Stress
Where medical evidence links the psychological state to the pregnancy or upcoming birth.
The Burden of Proof
If you report sick and state it is pregnancy-related, the force must normally accept this classification unless they have strong contrary evidence.
A GP note or midwife's letter stating 'sickness related to pregnancy' is definitive. If the force attempts to classify a related illness as 'General Sickness' to avoid the trigger, they are exposing themselves to an Employment Tribunal claim for pregnancy discrimination.
Tip: Explicitly ask your GP to include the words "pregnancy-related" on any fit note provided during the final trimester.
Section 04
The Financial Pivot
The most immediate concern for a police officer is the change in their payslip. Under Police Regulation 28, an officer is usually entitled to full sick pay for six months. However, once the 4-week trigger pulls you into maternity leave, you are no longer 'on sick leave'—you are 'on maternity leave'.
This means your pay moves from 100% (Sick Pay) to 100% (Occupational Maternity Pay - OMP) for the first 26 weeks. For officers in the first 26 weeks of MAT leave, there may be no net change in pay, but the 12-month 'MAT pay counter' has started earlier than expected.
Financial Risk Analysis
If you planned to work until week 39, but trigger at week 36, your 'Full Pay' (OMP) phase will end 3 weeks earlier than you budgeted for.
This pushes you into the Statutory (SMP) only phase or the Unpaid phase 3 weeks sooner.
Bottom Line: Triggering early effectively 'burns' your high-pay maternity weeks while you are still waiting for the baby to arrive.
Interaction with OMP/SMP Logic
Under current police terms (2026), you receive 26 weeks of full pay. If your maternity starts early due to the trigger, your 26-week OMP window begins immediately. For an officer who intended to start leave on the birth date, but goes sick 4 weeks early, they will reach the 'Half Pay' or 'SMP Only' stage when their baby is only 22 weeks old, rather than 26 weeks old.
Crucially, you cannot 'top up' your maternity pay with sick pay once the trigger has occurred. You essentially forfeit the remainder of your sick pay entitlement in favour of your maternity leave rights. While this is a regulatory necessity, it requires careful financial planning if you are prone to pregnancy-related health issues in the final month.
Section 05
Equality & Protections
The most powerful protection for pregnant officers comes from the Equality Act 2010. Pregnancy is a 'Protected Characteristic'. Any unfavourable treatment due to pregnancy-related sickness is direct discrimination.
Attendance Management Exclusion
Police forces use various trigger systems (Bradford Factor, 3 absences in 6 months, etc.) to flag officers for Unsatisfactory Performance Procedures (UPP) or 'Attendance Meetings'.
Sickness absence that is pregnancy-related MUST NOT be included in these scores. If your sergeant or inspector includes your pregnancy absence in a UPP review, they are acting unlawfully.
The 'Protected Period'
The protected period starts when you become pregnant and ends when your maternity leave ends (or when you return to work, whichever is later).
During this period, you have an absolute right to not be subjected to detriment for sickness. This includes being overlooked for promotion, being moved to a less desirable role upon return, or receiving a lower performance grade in your PDR because of your 'attendance levels'.
Snippet Target: Warnings
“Can pregnancy-related sickness count towards attendance warnings?”
No. Legally, any absence identified as pregnancy-related must be recorded but completely ignored for the purposes of attendance management triggers or disciplinary procedures. Counting such absence towards a warning constitutes unlawful pregnancy discrimination under the Equality Act 2010.
Section 06
Operational Reality
Policing is physically and mentally demanding. The '4-week rule' is often triggered not by a sudden medical emergency, but by the accumulative exhaustion of the 'frontline grind'. Even for officers on adjusted or light duties, the environment of a police station—constant radio noise, 12-hour shifts, and the stress of ongoing investigations—can exacerbate pregnancy symptoms.
Night shifts are a particular trigger point. While many forces allow pregnant officers to opt-out of nights, those who don't may find their health deteriorating rapidly in the final month. Fatigue is a legitimate medical reason for absence if a GP certifies it as pregnancy-linked exhaustion.
The Role of Occupational Health (OH)
OH cannot 'override' a GP's fit note, nor can they prevent the 4-week trigger if an officer goes sick. Their role is to facilitate your safety.
If you are struggling but don't want to trigger your MAT leave early, OH can recommend further adjustments, such as shortened shifts or homeworking (if the role allows). However, once sickness absence occurs within the 4-week window, the regulatory trigger takes precedence over any OH recommendation.
Section 07
Calculator Interaction
When the 4-week rule is triggered, it fundamentally alters the inputs of your maternity financial plan. If you have been using our Police Maternity Pay Calculator, you will need to re-run your numbers based on the new 'Trigger Date'.
An early start doesn't just change your pay dates; it can also impact your 2015 CARE pension accrual. Pension contributions are based on the pay you actually receive. If you move from 100% sick pay to 100% OMP, there is a technical shift in the 'source' of the pensionable earnings, though the net impact might be small.
Trigger Side-Effects
- OMP Phase: Your 26 weeks of full pay starts now, not on your baby's birth date.
- SMP Timeline: The 39-week statutory window moves forward.
- Return Date: Your 'Expected Return Date' will automatically move forward by the number of weeks the trigger was pulled.
Section 08
Officer Scenarios
Scenario A: The 3-Week Trigger
Context: PC Evans is 3 weeks (21 days) from her EWC. She calls in sick with pregnancy-linked exhaustion.
Outcome: Maternity leave is triggered immediately. Her planned leave start date (in 2 weeks time) is void. She is now on MAT leave.
Scenario B: The 5-Week Safety
Context: Sgt Clarke goes sick with pregnancy-related illness 5 weeks before her EWC.
Outcome: The 4-week rule does NOT apply. She remains on standard full-pay sick leave. Her maternity leave will start on her planned date.
Scenario C: The Disciplinary Buffer
Context: An officer has a high Bradford Factor and is on a sickness warning. She goes sick for 10 days due to morning sickness.
Outcome: These 10 days MUST be excluded from her sickness triggers. The warning cannot be progressed based on this absence.
Scenario D: The Half-Pay Bridge
Context: An officer is already on half-pay sick leave when she enters the 4-week trigger window. She is still sick.
Outcome: The trigger moves her to Maternity Leave, where she receives FULL PAY (OMP). This effectively gives her a pay rise during the sickness.
Scenario E: The Acting Rank Complication
Context: An officer in a temporary acting rank goes sick 2 weeks before EWC.
Outcome: Maternity starts. Her maternity pay (OMP) should be calculated based on her earnings in the 'AWE' window, which includes the acting rank pay.
Scenario F: Early Birth vs Sickness
Context: An officer is sick for 2 days within the window, triggering leave. The baby is born 3 days later.
Outcome: Maternity leave had already started on the day after the sickness. The birth doesn't 'restart' the leave; it simply continues.
Scenario G: The Annual Leave Trap
Context: Officer planned to take 2 weeks annual leave before maternity. She goes sick while on annual leave, 3 weeks before EWC.
Outcome: If the sickness is pregnancy-related, the annual leave is 'interrupted' and maternity leave starts day after first sickness day.
Scenario H: Force Discretion Error
Context: A sergeant tells an officer she 'doesn't have to trigger' if she doesn't want to.
Outcome: The sergeant is wrong. The rule is statutory and automatic. Payroll will likely override the sergeant's advice once the MATB1 and sickness dates are reconciled.
Section 09
Top 10 Errors
Authority Focus: Management Compliance
If you are a line manager, do not attempt to 'save' an officer's maternity leave by not reporting a pregnancy-related absence correctly. You are creating a major compliance risk and a potential discrimination claim for the force. The rule is for the officer's safety, and overriding it—even at their request—is a regulatory breach.
Equally, HR departments must ensure that automated payroll triggers are reconciled with sickness logs to prevent officers being paid sick pay when they should be on OMP, which can lead to complex overpayment recovery issues later.
Section 10
Authority FAQ Archive
Q: What is the 4-week rule for pregnancy sickness in the police?
A: The 4-week rule is a statutory provision where maternity leave and pay are automatically triggered if a police officer is absent from duty due to a pregnancy-related illness at any time during the four weeks before their Expected Week of Childbirth (EWC). This rule ensures that officers who become unwell near their due date transition directly to maternity leave for their safety and the child's wellbeing.
Q: Does pregnancy sickness trigger maternity leave automatically?
A: Yes, if the sickness occurs within the four weeks before the week the baby is due and the force classifies it as pregnancy-related. Leave starts automatically from the day after the first day of absence in that window.
Q: Can pregnancy sickness count towards attendance warnings?
A: No. Under the Equality Act 2010 and Police Regulations, any sickness absence that is pregnancy-related must be excluded from attendance management trigger calculations (such as Bradford Factor or UPP). Counting these absences towards disciplinary or warning thresholds is considered unlawful discrimination.
Q: Can I delay maternity leave if I'm sick 4 weeks before?
A: No. If the sickness is pregnancy-related, the trigger is statutory. You cannot 'opt-out' or delay the maternity start date once the sickness has occurred within that period. This is governed by the Maternity and Parental Leave Regulations 1999.
Q: Does the rule apply to adoption leave?
A: No. The 4-week trigger rule is specific to biological pregnancy and birth, intended for the physical protection of the mother and baby. Adoption leave starts on a date agreed between the officer and the force, usually based on the placement date.
Q: What if my baby is born during the 4-week window but before I report sick?
A: If the baby is born early, maternity leave starts automatically on the day after the birth. The sickness trigger doesn't apply because leave has already begun by virtue of the birth itself.
Q: Can my force override the trigger if I offer to work for free?
A: Absolutely not. This would be a gross violation of health and safety and employment laws. The force has a duty of care to ensure you are on leave. Voluntary work while on triggered maternity leave must strictly follow KIT day regulations.
Q: Does taking annual leave prevent the trigger?
A: No. If you go sick during annual leave that falls within the 4-week window, and it's pregnancy-related, the trigger still pulls you into maternity leave. You can usually 'reclaim' the annual leave to be used at a later date.
Q: How does the rule affect pension contributions?
A: Pension contributions are based on the pay you receive. If the trigger starts your maternity leave early, you begin your period of 'maternity pensionable service' sooner, which is generally protected for the first 39 weeks.
Q: What if I have COVID-19 in the 4-week window?
A: COVID-19 is generally not classified as pregnancy-related unless medical evidence shows your pregnancy made you susceptible or exacerbated the symptoms. If classified as general sickness, the trigger does not pull.
Q: Does the rule apply to part-time officers?
A: Yes. The 4-week rule is a statutory protection that applies to all employees and crown servants, regardless of their contracted hours. Part-time officers have the same trigger window based on their EWC.
Q: What if I am on a career break?
A: If you are on an active career break, you are not 'on duty' and cannot report sick in the same way. However, if you have a return date set, and your pregnancy sickness occurs within 4 weeks of EWC after that return date, the trigger applies.
Q: Is the 4-week rule the same in Scotland?
A: The 4-week trigger is part of the UK-wide statutory maternity framework. While some police administrative circulars vary, the core trigger rule remains consistent across all UK forces.
Q: Can a manager contact me during triggered leave?
A: Yes, "Reasonable Contact" is permitted and expected. Managers should check on your wellbeing and the baby, but they cannot require you to perform substantive work unless you agree to a KIT day.
Section 13
Clinical Context
The 4-week trigger rule exists because the final month of pregnancy is clinically distinct from the earlier stages. This is the period where the physiological load on the officer's body reaches its peak. In a policing context, this load is compounded by the inability to easily 'switch off' from the environmental stressors of the force.
Medical practitioners frequently encounter cases in the final month where an officer may not be 'critically ill' but is no longer 'fit for full duty' or even 'adjusted duty'. Conditions like gestational diabetes, mild pre-eclampsia, and severe SPD (Symphysis Pubis Dysfunction) often manifest or worsen in these final 28 days.
Medical Certification Nuance
When your GP issues a fit note in the 4-week window, the specific wording is vital. For the trigger to pull automatically under the Regulations, the note must clearly attribute the absence to the pregnancy.
A fit note stating "Back Pain" may lead to an administrative debate with HR. A fit note stating "Back pain due to pregnancy (SPD)" leaves the force with no legal room to maneuver; the trigger is immediate.
Officers should also be aware that an Occupational Health referral during this window is common. While OH can suggest further adjustments, such as 'work from home' only, if you are genuinely too unwell to work from home, you must be recorded as sick. The moment that 'sickness' label is applied in the final month, the transition to maternity leave is non-negotiable.
Section 14
Management Tactics
Avoid Informal Sickness
Do not allow officers to 'stay at home and do nothing' without recording it as sickness. This creates a data gap that can lead to insurance and pension liability issues.
Audit MATB1 Early
Ensure HR has a copy of the MATB1 before the 4-week window starts. This allows the payroll system to pre-flag the trigger window.
EWC Verification
The Expected Week of Childbirth is the only date that matters for the trigger. Check it against the Sunday start-date to define the window exactly.
Managers often worry that triggering maternity leave early will 'punish' the officer by shortening their time with the baby after the birth. While this is technically true for the 52-week entitlement period, managers must prioritize the legal and safety framework. A pregnant officer who is unwell and on duty (even adjusted duty) represents a significant risk to herself and the force.
A tactical approach to management involves having an open dialogue with the officer as they enter week 32. Discuss the 'Trigger Window' explicitly. If the officer is clearly struggling, encourage them to consider starting maternity leave early of their own volition rather than waiting for an illness to trigger it. This allows for a more controlled handover of duties and investigation files.
Section 15
The First 14 Days
Once triggered, the first two weeks of maternity leave are classified as 'Compulsory Maternity Leave'. During this time, it is legally prohibited for the force to allow you to perform any duty, even if you feel better after a few days of rest.
This compulsory period is intended to safeguard the health of the mother. If your baby is born during this time, the clock does not reset; you are simply in the compulsory phase of your ongoing maternity leave.
Operational Handover
If the trigger pulls you into leave unexpectedly, you may still have active cases or sensitive intelligence on your desktop.
The force may request an urgent handover brief. While you are on leave, this should ideally be handled by your supervisor accessing your files, but "Reasonable Contact" allows for a brief phone call to clarify file locations or passwords.
Section 16
Technical Glossary
AWE (Average Weekly Earnings)
The technical calculation of your earnings used by payroll to set your SMP rate, usually based on weeks 17-25.
Compulsory Maternity Leave
The first 2 weeks after birth (or trigger) where an officer is legally forbidden from working.
Detriment
Any negative treatment (e.g., missed bonus, poor review) resulting from exercising maternity or sickness rights.
EWC (Expected Week of Childbirth)
The Sunday-to-Saturday week in which your baby is due, as per your MATB1 form.
MATB1 Certificate
The official medical form issued by your midwife after week 20 that confirms your pregnancy and due date.
OMP (Occupational Maternity Pay)
The enhanced pay provided under Police Regulations (currently 26 weeks full pay).
PNB (Police Negotiating Board)
The historic body that agreed many of the standard family-leave terms still used in 2026.
Protected Period
The window from the start of pregnancy to the end of maternity leave where extra legal guards against discrimination apply.
Qualifying Week
The 15th week before your EWC, used to determine if you have enough service for SMP.
SAP (Statutory Adoption Pay)
The equivalent of SMP for officers who are adopting children.
SMP (Statutory Maternity Pay)
The government-mandated baseline pay for mothers, currently paid for 39 weeks.
Trigger Window
The 28 days immediately preceding the Sunday of your Expected Week of Childbirth.
Section 17
Case Law & Precedent
The application of the 4-week trigger and the protection of pregnant officers is heavily influenced by European and UK case law. One of the primary cases is Jimenez Melgar v Ayuntamiento de Los Barrios, which clarified that non-renewal of a fixed-term contract due to pregnancy is discriminatory. In a policing context, this extends to 'detriment' such as being passed over for temporary postings.
Another critical precedent is Tele-Danmark A/S v Handels-og Kontorfunktionærernes Forbund i Danmark (HK), where the court ruled that an employer cannot dismiss an employee for pregnancy even if they were hired for a fixed term and were aware of the pregnancy at the time of hiring. This reinforces the 'absolute' nature of the protected period.
The 'No-Fault' Principle
Legal precedent establishes that pregnancy-related sickness is effectively 'no-fault' absence.
This means it cannot be used to justify any negative outcome, including 'loss of opportunity'. If an officer is triggered into maternity 4 weeks early, and a promotion process begins in week 3 of that leave, the force must ensure she is not disadvantaged in the selection process due to her absence.
Note: Most forces now conduct interviews via video-link for officers on maternity leave to ensure full compliance with the Equality Act.
Section 11
Technical Framework
This authority guide is based on the statutory floor provided by the Employment Rights Act 1996 and the Maternity and Parental Leave etc. Regulations 1999. In the context of policing, these are administered under Annex L of the Police Regulations 2003.
The protection against attendance management triggers is guaranteed by the Equality Act 2010, specifically sections related to 'Pregnancy and Maternity Discrimination'. Case law, such as Jimenez Melgar v Ayuntamiento de Los Barrios, has established that pregnancy-related sickness cannot be used as a ground for dismissal or detriment.
Next Tactical Steps
The 4-week sickness trigger is a gateway into the wider world of police maternity finance. Now that you understand the automatic start, we recommend reviewing our Police Maternity Pay Masterguide to see what happens after your leave begins.
If your leave starts early, you may want to use those extra weeks to plan your return. Explore KIT Days Explained (2026) to understand how you can maintain operational touchpoints without ending your maternity phase early.
Finally, ensure your pension profile is updated. Use the Pension Impact Tool to see exactly how an early trigger affects your revaluation across the 2015 scheme.
Authority Statement
Independent explainer • Not legal advice • Verified Feb 2026
Disclaimer: This guide is provided for informational purposes only and does not constitute technical legal advice. Police Regulations and Force Policies are subject to change. Always consult your Federation representative or HR department for specific case details.