# Built for two babies, not one baby twice _Twins get a delivery window that expects them, two feed timers that run at the same time, and a Home card, Live Activity, Lock Screen widget and Apple Watch page each. Your medical due date stays exactly where it is._ - Source: https://proba.baby/en/twins - Language: English - Last verified: v1.0.4 · 7 Sep 2026 - **2+** — Live timers running at once - **37+0** — Twin target, window 34+0–38+6 - **Free** — Unlimited babies, no paid gate - **5** — Widgets you can pin per baby ## A timeline that expects two Twins arrive earlier than singletons, so the countdown, the calendar band and the birth-prep deadlines move with them. The medical 40-week due date is never overwritten — the app shows both. - **Twin-adjusted delivery window** — Twins count toward a 37+0 target inside a 34+0–38+6 window; triplets toward 35+0 inside 32+0–35+6. One table drives every date, grounded in ACOG Practice Bulletin 231 and NICE NG137, and your medical 40-week due date rides along untouched. - **Chorionicity, from your scan** — Record DCDA, MCDA, MCMA or “not sure yet” straight off the 11–14 week scan report — it is data entry, never a medical question to answer yourself. MCDA moves the target to 36+0 and MCMA to 33+0, and the answer travels into the doctor-visit summary and its PDF. - **Twin weight-gain targets** — The IOM 2009 provisional twin guidelines, stratified by pre-pregnancy BMI: 16.8–24.5 kg for normal, 14.1–22.7 for overweight, 11.3–19.1 for obese. IOM publishes no twin range for underweight, so the app shows none instead of inventing one. - **36 twin notes, week by week** — Every week from 4 to 38 carries its own twin note, plus one collapsed note for 39 and beyond — 36 in all, in 32 languages, source-checked against the guidelines before translation. They appear on the weekly Baby tab, the Overview tips card, the Weekly Baby Size tool and the timeline row. - **Twin scan expectations** — Medical Tests adds a twin schedule card to each trimester — expectation-setting, not extra checklist items, with no risk numbers and no self-triage. Shared-placenta twins get one more line: growth scans are usually offered every two weeks from 16 weeks, with your care team confirming the cadence. - **Bags packed for two** — The hospital-bag planner scales baby items by your declared count and seeds Twins or Triplets from the pregnancy profile before you start, without ever overwriting a choice you already saved. The Baby Registry scales its quantities ×2 or ×3 from its own preference. ## Two babies, one phone, at the same time Version 1.0.4 rebuilt the tracker around a per-baby session engine. Baby A's feed timer and Baby B's feed timer now run together on one device, each with its own pause math, its own record and its own reminder. - **Two timers at once** — One phone runs a live feeding or sleep timer for each baby, and starting a sleep only ends that baby's feed. The dock pill picks whose flow you are driving instead of switching the whole app, and the twin you are not looking at keeps a ticking chip you can tap to flip. - **A Home card per baby** — Every active baby gets its own hero card on Home, named once there are two of them. On a wide iPad layout the two heroes sit side by side in their own columns, each with its own today tiles: next side, last diaper, feeds and longest sleep. - **Live Activities per baby** — Feeding, sleep and reminder Live Activities are keyed to a baby and coexist, and the Lock Screen buttons act on the baby they name. Tapping one twin's Live Activity opens the log dock with that twin already selected, and eight widget kinds — the four Lock Screen ones included — can each be pinned to one baby. - **A Watch page per baby** — Apple Watch carries baby chips through Feeding, Sleep, Diaper, the Dashboard and the Day Clock, and diaper logging has a Both chip that writes one log per baby. The Watch mirrors one timed session at a time by design — two live timers is a phone capability. - **Compare, side by side** — Compare is a first-class tab: feeds, sleep and diapers per day as A-versus-B bars, plus one WHO growth chart with both babies overlaid and a named legend. It is descriptive — it does not score, flag or alert on a difference between your babies. - **Corrected age, done properly** — For a baby born before 37+0 the app subtracts (40 − gestational age) × 7 days and shows corrected age until 24 months, the way pediatricians track it. It drives milestones and WHO growth percentiles, and it deliberately never touches vaccination schedules. - **A solid food log, per baby** — The solid food log sits in the dock as an instant tap, never a timer, with a by-type breakdown in the Track tab. When solids start is stored per baby and read off corrected age, because twins differ and a preterm twin should not be prompted early. - **One tap adds their twin** — Confirm a twin birth once and you get one profile per declared baby in a single flow, with a shared birth date and delivery type. If a declared twin is still missing afterwards, an “Add their twin?” prompt creates the sibling with the same birth date, delivery type and weeks of pregnancy at birth. ## From “how many babies?” to two timers One answer during onboarding changes the math for the whole journey. There is nothing else to set up. - **Say how many** — Onboarding asks how many babies right under the status card — One, Twins or Triplets+. One is preselected, so a single baby never costs an extra tap, and the answer pre-fills your pregnancy profile. - **The timeline adjusts** — The countdown, the calendar delivery band, the birth-prep deadlines and the hospital bag all move to the twin target — 37+0, or 36+0 and 33+0 once you record MCDA or MCMA. Change the count and the app offers a one-tap re-export instead of rewriting your calendar silently. - **Confirm the birth once** — One confirmation creates one baby profile per declared baby — name, sex, weight and length in their own rows, sharing a birth date and delivery type. Every baby moves into the Baby module, not just the first one. - **Log in tandem** — Two timers run together, and the twin the pill is not on keeps a live chip that flips the pill when tapped. The feeding, sleep and diaper sheets carry [A] [B] [Both] chips — the aggregate reads All once there are three or more babies. - **Compare when you want** — The Compare tab puts feeds, sleep and diapers per day beside each other and overlays both babies on one WHO growth curve. With three or more babies you choose the pair, and the comparison keeps its own selection instead of following the rest of the app. ## The twin features we left out on purpose A few things sound useful on a feature list and would be wrong in an app. Here is what ProbaBaby refuses, and why. - **No per-baby kick counts** — Telling which twin moved is not reliable, and the RCOG movement guidance the counter follows is written for single babies. So the kick counter tracks your babies' overall pattern together, on iPhone and Apple Watch, and says to contact your care team if that usual pattern changes. - **No discordance alerts** — The Compare tab shows what your own logs and measurements say, and stops there. There is no growth-discordance scoring, no TTTS monitoring and no risk percentage — scans and your care team do that work, and the app says so rather than imitating them. - **No NICU mode** — There is no NICU tracking module, feed-and-output mode or NICU dashboard. The only NICU content in the app is educational: a card explaining NICU levels inside the Early Birth Risk section. ## Two babies cost the same as one There is no baby limit, no per-baby credit factor and no premium gate on multiples: every tracking feature works the same whether you have one baby or four. Credits are only ever spent on AI baby-face predictions, and every new account starts with five of them. ## FAQ **Is ProbaBaby a good twin pregnancy tracker?** Twins are what version 1.0.4 was built around, released 4 September 2026. On the pregnancy side you get a twin-adjusted delivery window, chorionicity, 36 week-by-week twin notes, twin medical-test cards and IOM 2009 twin weight-gain targets. After the birth the tracker runs a live timer per baby, with a Compare tab for the two of them. None of it sits behind a paywall. **Can I feed both babies at the same time in the app?** Yes, on iPhone. One device runs Baby A's feed timer and Baby B's feed timer together, each with its own pause math, its own record and its own reminder. The dock pill selects whose flow you are driving rather than switching the app, and the other twin keeps a ticking chip you can tap. For untimed logging, the feeding, sleep and diaper sheets have [A] [B] [Both] chips. **Does it work for triplets, or more?** Triplets get their own target of 35+0 inside a 32+0–35+6 window, the aggregate log chip reads All instead of Both, and the Compare tab adds an explicit pair selector. Two features stay twins-only because their wording says twins: chorionicity and the weekly twin notes. For four or more babies the app shows a text range rather than a computed date, and the number of babies you can track after birth is not capped. **How is the due date different for twins?** Your medical due date does not change — it stays 40 weeks — and the app adds a twin target beside it. For twins that target is 37+0 inside a 34+0 to 38+6 window; record MCDA and it moves to 36+0, MCMA to 33+0. The countdown, the calendar band and the birth-prep deadlines follow the target, so a hospital-bag deadline cannot land after a typical twin delivery. The table is grounded in ACOG Practice Bulletin 231 and NICE NG137. **What is chorionicity, and why does the app ask?** Chorionicity is whether your babies share a placenta and a sac; your 11–14 week scan report names it DCDA, MCDA or MCMA. The app asks you to copy what the report says rather than answer a medical question yourself, and “not sure yet” is a proper answer you can change any time. It matters because it moves the planned-birth target by up to four weeks, and monochorionic profiles also see a line about the two-weekly growth scans usually offered from 16 weeks. **Does it handle corrected age for premature twins?** Yes. Each baby stores the weeks of pregnancy at birth, and for a baby born before 37+0 the app subtracts (40 − gestational age) × 7 days, showing corrected age until 24 months — the AAP convention pediatricians use. It drives milestones and WHO growth percentiles, and both ages are shown together, as in “8 weeks old · 5 weeks corrected”. It never touches vaccination schedules, which stay chronological. **Does the Apple Watch work with twins?** Yes, with one limit worth stating plainly. The Watch carries baby chips through Feeding, Sleep, Diaper, the Dashboard and the Day Clock, diaper logging has a Both chip that writes one log per baby, and a twin facts card shows the window opening at 34+0, the target at 37+0 and the window closing at 38+6. What it does not do is run two timed sessions at once: the Watch mirrors one session by design, and two live timers is a phone capability. **Is it free for two babies, and which languages does it speak?** Tracking two babies is free, and so is tracking four. There is no baby limit, no per-baby credit factor and no premium gate; credits are only for AI baby-face predictions, and each new account starts with five. The app ships in 32 languages, and every user-facing twin string — all 36 weekly notes, the chorionicity questions, the twin test cards and the corrected-age copy — is translated into all of them. --- ProbaBaby (listed on the App Store as “Pregnancy & Baby Tracker - PB”) is a free iPhone, iPad and Apple Watch app for pregnancy, newborn and postpartum tracking, built for twins, in 32 in-app languages, with an optional AI baby-face prediction that computes Mendelian genetics (Punnett squares) from the traits you enter before any image is generated. Tracking, tools, PDF reports and family sharing are free; only AI predictions use credits — 5 starter credits cover your first Scientific prediction — and no subscription is required. Requires iOS 26 or later. Not available on Android.