What is TrimesterCare?

TrimesterCare is a maternal and child health assistant that answers antenatal, delivery and immunisation questions over WhatsApp and SMS in Nigerian Pidgin, Hausa, Yorùbá, Igbo and English. Every reply is retrieved from a fixed index of WHO and Nigerian national guidelines and checked by a deterministic red-flag rules layer before it is sent.

Is TrimesterCare an emergency service?

No. TrimesterCare is not an emergency service and does not summon an ambulance. If you are bleeding heavily, having fits, or someone is unconscious, go to the nearest health facility immediately rather than waiting for a reply.

Does TrimesterCare diagnose or prescribe?

No. TrimesterCare does not name a condition a clinician has not confirmed, does not interpret test results, and does not give dosages beyond what the national schedule already publishes. It relays published guidance and routes anything above routine to a health worker.

How does TrimesterCare stop the model from making things up?

Answers are composed only from passages retrieved out of a versioned index of six vetted guideline documents. Spans that cannot be traced to retrieved text are rejected before send. If no passage clears the retrieval threshold, TrimesterCare says it does not know and routes the mother to a health worker rather than generating an answer from model memory.

What happens when a mother reports a danger sign?

A deterministic rules layer evaluates the reported symptoms against the red-flag rule set, filtered by gestational age, before any text is generated. It can only escalate triage, never lower it, and the model cannot overrule it. A fired go-now rule produces an immediate instruction to attend a facility, with the source guideline attached.

Which languages does TrimesterCare support?

Nigerian Pidgin, Hausa, Yorùbá, Igbo and English. TrimesterCare replies in the language the question arrives in. Every translated string is reviewed and signed off by a native speaker before it reaches a mother, because machine-plausible translation is not an acceptable standard in a health context.

Which guidelines does TrimesterCare use?

WHO recommendations on antenatal care (2016), WHO Managing Complications in Pregnancy and Childbirth (2017), WHO Pregnancy, Childbirth, Postpartum and Newborn Care (2015), WHO postnatal care recommendations (2022), the Nigerian National Standing Orders for Community Health Practitioners (2015), and the NPHCDA National Routine Immunisation Schedule (2023).

Does TrimesterCare work without internet or a smartphone?

Yes. WhatsApp is the primary channel, and SMS is a full fallback: if a WhatsApp message is undelivered for six hours it is retried over SMS. Reminders and answers are text-only and designed to be legible on a feature phone and on a poor connection.

What reminders does TrimesterCare send?

The eight antenatal contacts WHO recommends, plus the Nigerian national routine immunisation schedule from birth to twelve months. Reminders are scheduled from the confirmed gestational age, sent ahead of the due date rather than on it, and rebased automatically whenever a health worker corrects the gestational age.

What data does TrimesterCare hold about a mother?

The phone number the conversation arrives on, the gestational age she or a health worker confirmed, the reminder schedule derived from it, and the message content needed to answer and to audit. She can stop reminders at any time by replying STOP, and request deletion of her record by replying DELETE or contacting privacy@trimestercare.com.

Has TrimesterCare been clinically evaluated?

Not independently, and the page says so. TrimesterCare is pre-pilot. Figures presented as targets are labelled as targets, no impact numbers are claimed, and the team is seeking a state primary healthcare board for a supervised pilot and obstetricians to adjudicate the rule set.

Does TrimesterCare replace health workers?

No. It routes to them rather than around them. Every reply ends with an escalation line appended by the response template, not generated by the model, and high-risk cases are directed to a facility the same day. The design intent is caseload relief for community health extension workers, not substitution.

Live on WhatsApp + SMSNigeriaSDG 3 & 5

Ask about yourpregnancy. Anytime.In your language.

A mother messages in Pidgin at two in the morning. TrimesterCare answers from WHO and Nigerian national guidelines — retrieved, cited, and checked against a deterministic red-flag rules layer before a single word is sent. It does not improvise. When it does not know, it says so and points her to a health worker.

Read the safety model Send it a message →

Week28/III

Due at this gestation

Screen for gestational diabetes

Danger signs the rules layer is watching

Bleeding
Convulsions
Difficulty breathing
Headache with blurred vision
Facial swelling
Reduced fetal movement
Leaking fluid

WHO ANC 2016NG NSO 2015NPHCDA RI 2023Third trimester. Preterm signals carry the highest escalation weight.

Nigeria carries close to a quarter of the world’s maternal deaths.

Almost all of them follow signs that were recognisable hours before they became emergencies: bleeding, a headache that will not lift, a baby that has stopped moving. The clinical knowledge to act on those signs exists and is public.

It is written in English, in PDFs, behind data plans, for readers who already know the word “pre-eclampsia”. Recognition is a language problem long before it is a medical one.

“The delay that kills is rarely the one at the hospital door. It is the hours before anyone was sure it was serious.”
The three-delays model · Thaddeus & Maine, 1994

011,047per 100,000 live birthsNigeria's maternal mortality ratioUN MMEIG / WHO2020 estimate
02≈28%of the global totalShare of the world's maternal deaths occurring in NigeriaUN MMEIG / WHO2020 estimate
038recommended contactsAntenatal contacts WHO recommends per pregnancyWHO ANC recommendations2016

It never freestyles.

Four stages sit between a mother’s message and TrimesterCare’s reply. Three of them are deterministic. The model is only ever allowed to phrase what retrieval already found.

Thread · WhatsApp02:14

My belle dey pain me since morning and pikin no dey kick like before. I be 28 weeks.

Nigerian Pidgin · inbound

Pikin wey no dey move well for 28 weeks na danger sign. Abeg go clinic today — no wait till morning.

Before you go: lie for your left side, count the kicks wey you feel for two hours. Carry your ANC card.

WHO ANC 2016 §B.1.6NG NSO 2015 §12.4

◆ Always see a health worker. TrimesterCare cannot examine you.

Go to a clinic nowrule R-063 · 1.9 s

Parse
1/4
Language and gestational age are resolved first. Everything downstream depends on knowing which week she is in.
detect_language
pcm-NG · conf 0.94
resolve_gestation
28+2 weeks · from ANC record
extract_symptoms
abdominal-pain, reduced-movement
normalise
pidgin → clinical vocabulary
Retrieve
2/4
Passages are pulled from a fixed, versioned index of vetted guidelines. Nothing outside the index can reach the answer.
index
who-anc-2016 · v4 · 1,208 passages
top_1
WHO ANC 2016 §B.1.6 · 0.86
top_2
WHO MCPC 2017 §S-119 · 0.81
top_3
NG NSO 2015 §12.4 · 0.77
threshold
0.62 · passed
Rule check
3/4
A deterministic layer runs in front of the model. It can only escalate, and it is never asked to reassure.
eval_rules
15 candidates · gestation-filtered
R-063
reduced movement ≥ 28 wk — FIRED
R-093
abdominal pain — fired
triage
go-now (highest wins)
Compose
4/4
The reply is assembled from retrieved passages only, in her language, with citations attached and the escalation line appended by the template — not by the model.
grounding
3 passages · 0 ungrounded spans
translate
→ pcm-NG · reviewed glossary
escalation
appended · non-optional
reminder
follow-up scheduled · +12 h
latency
1.9 s · SMS fallback ready

The rules layer runs first, and it can only escalate.

Before any retrieval result is phrased, a deterministic evaluator checks the reported symptoms against the red-flag rule set, filtered by gestational age. It has no ability to downgrade a danger signal. Select symptoms below and move the week — this is the same evaluator that ships.

Red-flag rule set · demonstration subset (15 of the deployed set)

R-011Go now4–42 wk
Convulsions or fits
Emergency. Eclampsia until proven otherwise — call for transport.
WHO MCPC 2017 · S-49
R-018Go now20–42 wk
Severe headache with blurred vision, ≥ 20 weeks
Assess for pre-eclampsia. Blood pressure and urine protein today.
WHO MCPC 2017 · S-43
R-041Go now4–19 wk
Any vaginal bleeding before 20 weeks
Possible miscarriage or ectopic pregnancy. Be seen today.
WHO MCPC 2017 · S-7
R-042Go now20–42 wk
Any vaginal bleeding from 20 weeks
Antepartum haemorrhage. Do not examine at home — go now.
WHO MCPC 2017 · S-17
R-044Go now20–42 wk
Bleeding with severe abdominal pain, ≥ 20 weeks
Suspected placental abruption. Emergency transport.
WHO MCPC 2017 · S-18
R-052Go now4–42 wk
Difficulty breathing at rest
Assess for severe anaemia, heart failure or pneumonia.
WHO MCPC 2017 · S-136
R-063 (fired)Go now28–42 wk
Reduced fetal movement from 28 weeks
Fetal wellbeing check the same day. Do not wait until morning.
WHO ANC 2016 · B.1.6
R-070Go now4–36 wk
Leaking fluid before 37 weeks
Preterm rupture of membranes. Infection risk — be seen today.
WHO MCPC 2017 · S-136
R-072Go now4–42 wk
Fever with abdominal pain
Possible intrauterine or urinary infection. Same-day review.
WHO MCPC 2017 · S-107
R-025Go now20–42 wk
Facial swelling with headache, ≥ 20 weeks
Pre-eclampsia screen today — BP and urine protein.
WHO ANC 2016 · B.1.1
R-081Watch4–42 wk
Fever ≥ 38 °C alone
Malaria and infection are common causes. Be tested within 24 hours.
WHO ANC 2016 · A.9
R-086Watch20–42 wk
Sudden swelling of face or hands, ≥ 20 weeks
Have blood pressure checked within 24 hours.
WHO ANC 2016 · B.1.1
R-090Watch4–42 wk
Vomiting, unable to keep fluids down
Dehydration risk. Seek care within 24 hours if it continues.
WHO ANC 2016 · B.3.1
R-093Watch4–42 wk
Severe abdominal pain alone
Describe the pain to a health worker within 24 hours.
WHO MCPC 2017 · S-119
R-095Watch4–27 wk
Reduced movement before 28 weeks
Movement is not yet a reliable signal this early. Mention it at your next contact.
WHO ANC 2016 · B.1.6

Red-flag rules. Rows matching the current symptom and gestation selection are marked as fired.
Rule	Trigger	Weeks	Triage	Action	Source
R-011	Convulsions or fits	4–42	Go now	Emergency. Eclampsia until proven otherwise — call for transport.	WHO MCPC 2017 · S-49
R-018	Severe headache with blurred vision, ≥ 20 weeks	20–42	Go now	Assess for pre-eclampsia. Blood pressure and urine protein today.	WHO MCPC 2017 · S-43
R-041	Any vaginal bleeding before 20 weeks	4–19	Go now	Possible miscarriage or ectopic pregnancy. Be seen today.	WHO MCPC 2017 · S-7
R-042	Any vaginal bleeding from 20 weeks	20–42	Go now	Antepartum haemorrhage. Do not examine at home — go now.	WHO MCPC 2017 · S-17
R-044	Bleeding with severe abdominal pain, ≥ 20 weeks	20–42	Go now	Suspected placental abruption. Emergency transport.	WHO MCPC 2017 · S-18
R-052	Difficulty breathing at rest	4–42	Go now	Assess for severe anaemia, heart failure or pneumonia.	WHO MCPC 2017 · S-136
R-063 (fired)	Reduced fetal movement from 28 weeks	28–42	Go now	Fetal wellbeing check the same day. Do not wait until morning.	WHO ANC 2016 · B.1.6
R-070	Leaking fluid before 37 weeks	4–36	Go now	Preterm rupture of membranes. Infection risk — be seen today.	WHO MCPC 2017 · S-136
R-072	Fever with abdominal pain	4–42	Go now	Possible intrauterine or urinary infection. Same-day review.	WHO MCPC 2017 · S-107
R-025	Facial swelling with headache, ≥ 20 weeks	20–42	Go now	Pre-eclampsia screen today — BP and urine protein.	WHO ANC 2016 · B.1.1
R-081	Fever ≥ 38 °C alone	4–42	Watch	Malaria and infection are common causes. Be tested within 24 hours.	WHO ANC 2016 · A.9
R-086	Sudden swelling of face or hands, ≥ 20 weeks	20–42	Watch	Have blood pressure checked within 24 hours.	WHO ANC 2016 · B.1.1
R-090	Vomiting, unable to keep fluids down	4–42	Watch	Dehydration risk. Seek care within 24 hours if it continues.	WHO ANC 2016 · B.3.1
R-093	Severe abdominal pain alone	4–42	Watch	Describe the pain to a health worker within 24 hours.	WHO MCPC 2017 · S-119
R-095	Reduced movement before 28 weeks	4–27	Watch	Movement is not yet a reliable signal this early. Mention it at your next contact.	WHO ANC 2016 · B.1.6

Send it a message and watch it refuse to guess.

This console runs the real evaluator in your browser: the same language detection, the same gestational-age parser, the same red-flag rule set, and the same refusal threshold. Nothing is scripted. Try to make it say something it should not.

Simulated retrieval index and simulated latency. No message leaves your device and nothing is stored.

WhatsApp · +234 800 000 0000

demo line

Empty thread. Pick a scenario below, or type a question the way a mother would actually type it — in Pidgin, Hausa, Yorùbá, Igbo or English.

Execution trace

The trace prints here: detected language, resolved gestational age, extracted symptoms, retrieved passages with their scores, every rule that fired, and the grounding check before send.

The rule set here is the demonstration subset published in the ledger above. The deployed system carries the full set and a versioned guideline index; both are reproducible for audit. Translated template strings are pending native-speaker sign-off.

She should not have to translate herself first.

English is Nigeria’s official language and almost nobody’s first one. TrimesterCare reads and replies in the language the question arrives in, including Pidgin — which most health information ignores entirely, and which more Nigerians speak than any other.

Reading

Nigerian Pidgin · ~120M speakers

“My abdomen has been painful since morning. I am seven months pregnant.” — the same message, resolved to gestational week 28 and the symptoms abdominal pain and reduced fetal movement before retrieval begins.

Sample strings above are pending sign-off by native speakers of each language. In a clinical product, machine-plausible translation is not an acceptable standard, and no string reaches a mother without human review.

The other half is remembering.

Eight antenatal contacts and six immunisation visits over eighteen months, each one easy to lose to a harvest, a market day, or a phone that ran out of credit. TrimesterCare schedules every one of them from the confirmed gestational age and sends the reminder ahead of the date, not on it.

Reminder sent

ANC 3 · 5 days before · WhatsApp, with SMS fallback

Delivery is retried on SMS if WhatsApp is undelivered for six hours, and the schedule rebases automatically whenever a health worker corrects the gestational age. A missed visit is followed up once, not nagged.

Outbound · Antenatal contacten-NG shown

Antenatal visit 3 of 8 is due. Ask for your tetanus injection and your malaria prevention tablets while you are there.

Sent in her chosen language. Reply STOP to end reminders, LATER to defer one visit.

The guardrails are the product.

Anyone can put a language model in front of a pregnant woman. The engineering that matters is everything we stop it from doing. These six constraints are architectural — they hold when the model is wrong, when the network is bad, and when nobody is watching.

No answer without a source.
Every reply carries the guideline passage it was built from. Spans that cannot be traced to retrieved text are rejected before send, not flagged afterwards.
A refusal is a correct answer.
Below the retrieval threshold TrimesterCare says it does not know and routes to a health worker. Refusal rate is a monitored quality metric, not a defect.
The rules layer has no downgrade path.
Deterministic, gestation-filtered, evaluated before generation. It can raise triage from routine to go-now. It cannot lower it, and the model cannot overrule it.
Every high-risk reply ends with a human.
The escalation line is appended by the response template after generation. There is no path through the code in which the model can omit it.
It does not diagnose and does not prescribe.
No dosages beyond what the national schedule already publishes, no interpretation of test results, no naming of a condition a clinician has not confirmed.
The corpus is versioned and frozen.
Answers are reproducible. For any reply, we can show the index version, the retrieved passages and the rules that fired — years later, in an audit.

What it is allowed to read.

The entire retrievable universe, in full. Nothing else is reachable at answer time — no open web, no model recall, no plausible-sounding memory of a guideline.

WHO-ANC-2016WHO recommendations on antenatal care for a positive pregnancy experienceWorld Health Organization · 201649 sections
WHO-MCPC-2017Managing Complications in Pregnancy and ChildbirthWorld Health Organization · 201762 sections
WHO-PCPNC-2015Pregnancy, Childbirth, Postpartum and Newborn CareWorld Health Organization · 201538 sections
WHO-PNC-2022Recommendations on maternal and newborn care for a positive postnatal experienceWorld Health Organization · 202227 sections
NG-NSO-2015National Standing Orders for Community Health PractitionersFederal Ministry of Health, Nigeria · 201531 sections
NG-RI-2023National Routine Immunization ScheduleNPHCDA, Nigeria · 20239 sections

What we can claim today, and what we cannot.

TrimesterCare has not completed an independent clinical evaluation. Every row below is tagged with what it actually is. Nothing on this page reports an impact figure, because we do not yet have one worth reporting.

Enforced
100%
Replies carrying at least one citation
Structural, not statistical — an uncited reply cannot be sent.
System fact
216
Guideline sections indexed
Across six vetted documents. Listed in full below.
System fact
5
Languages in production
Pidgin, Hausa, Yorùbá, Igbo, English.
Target · unverified
≥ 99%
Red-flag recall on the adjudicated test set
Acceptance threshold for release. Not yet independently evaluated.
Target · unverified
≤ 8%
Refusal rate on out-of-corpus questions
Design target. Too low would indicate over-answering.
Target · unverified
< 3 s
Median time to first reply
Design target, including SMS fallback path.

It lives where she already is.

No app to install, no account to create, no data plan to hold open. WhatsApp where there is data, SMS where there is not, and the same conversation either way — because the mother who needs this most is the one with the worst phone and the weakest signal.

placeholder

+234 800 000 0000

Primary channel. Rich text, message history, delivery receipts. Runs on the WhatsApp Business API.

Open the console instead →

SMS short code

placeholder

40404

Full fallback, not a degraded one. A WhatsApp message undelivered for six hours is retried here. Works on any handset made in the last twenty years.

24/7, automated. Not monitored by a clinician.

Keywords, in any supported language

STOP: End all reminders immediately.
LATER: Defer the next reminder by one visit.
DELETE: Erase the record. Confirmed by reply.
MY DATA: Return a summary of what is held.
LANGUAGE: Change the language replies are sent in.
HELP: List these keywords in the current language.

TrimesterCare is pre-pilot: neither number above is commissioned, and both are shown so that the channel design can be reviewed, not dialled. The working demonstration is the console above. Live numbers will be published here when a supervised pilot is agreed with a state primary healthcare board.

Questions we get asked in the second meeting.

Answered here rather than in a follow-up email. If something you need is missing, the technical brief goes further — ask for it.

01
What is TrimesterCare?
TrimesterCare is a maternal and child health assistant that answers antenatal, delivery and immunisation questions over WhatsApp and SMS in Nigerian Pidgin, Hausa, Yorùbá, Igbo and English. Every reply is retrieved from a fixed index of WHO and Nigerian national guidelines and checked by a deterministic red-flag rules layer before it is sent.
02
Is TrimesterCare an emergency service?
No. TrimesterCare is not an emergency service and does not summon an ambulance. If you are bleeding heavily, having fits, or someone is unconscious, go to the nearest health facility immediately rather than waiting for a reply.
03
Does TrimesterCare diagnose or prescribe?
No. TrimesterCare does not name a condition a clinician has not confirmed, does not interpret test results, and does not give dosages beyond what the national schedule already publishes. It relays published guidance and routes anything above routine to a health worker.
04
How does TrimesterCare stop the model from making things up?
Answers are composed only from passages retrieved out of a versioned index of six vetted guideline documents. Spans that cannot be traced to retrieved text are rejected before send. If no passage clears the retrieval threshold, TrimesterCare says it does not know and routes the mother to a health worker rather than generating an answer from model memory.
05
What happens when a mother reports a danger sign?
A deterministic rules layer evaluates the reported symptoms against the red-flag rule set, filtered by gestational age, before any text is generated. It can only escalate triage, never lower it, and the model cannot overrule it. A fired go-now rule produces an immediate instruction to attend a facility, with the source guideline attached.
06
Which languages does TrimesterCare support?
Nigerian Pidgin, Hausa, Yorùbá, Igbo and English. TrimesterCare replies in the language the question arrives in. Every translated string is reviewed and signed off by a native speaker before it reaches a mother, because machine-plausible translation is not an acceptable standard in a health context.
07
Which guidelines does TrimesterCare use?
WHO recommendations on antenatal care (2016), WHO Managing Complications in Pregnancy and Childbirth (2017), WHO Pregnancy, Childbirth, Postpartum and Newborn Care (2015), WHO postnatal care recommendations (2022), the Nigerian National Standing Orders for Community Health Practitioners (2015), and the NPHCDA National Routine Immunisation Schedule (2023).
08
Does TrimesterCare work without internet or a smartphone?
Yes. WhatsApp is the primary channel, and SMS is a full fallback: if a WhatsApp message is undelivered for six hours it is retried over SMS. Reminders and answers are text-only and designed to be legible on a feature phone and on a poor connection.
09
What reminders does TrimesterCare send?
The eight antenatal contacts WHO recommends, plus the Nigerian national routine immunisation schedule from birth to twelve months. Reminders are scheduled from the confirmed gestational age, sent ahead of the due date rather than on it, and rebased automatically whenever a health worker corrects the gestational age.
10
What data does TrimesterCare hold about a mother?
The phone number the conversation arrives on, the gestational age she or a health worker confirmed, the reminder schedule derived from it, and the message content needed to answer and to audit. She can stop reminders at any time by replying STOP, and request deletion of her record by replying DELETE or contacting privacy@trimestercare.com.
11
Has TrimesterCare been clinically evaluated?
Not independently, and the page says so. TrimesterCare is pre-pilot. Figures presented as targets are labelled as targets, no impact numbers are claimed, and the team is seeking a state primary healthcare board for a supervised pilot and obstetricians to adjudicate the rule set.
12
Does TrimesterCare replace health workers?
No. It routes to them rather than around them. Every reply ends with an escalation line appended by the response template, not generated by the model, and high-risk cases are directed to a facility the same day. The design intent is caseload relief for community health extension workers, not substitution.