diff --git a/lib/sympto/index.js b/lib/sympto/index.js
index 2d2f244..e32f8a2 100644
--- a/lib/sympto/index.js
+++ b/lib/sympto/index.js
@@ -7,23 +7,25 @@ export default function ({ cycle, previousCycle }) {
   // TODO check for basic stuff, throw if nonexistent
   const status = {
     assumeFertility: true,
-    phases: {
-      periOvulatory: {
-        start: {
-          date: null
-        },
-        cycleDays: null
-      }
-    }
+    phases: {}
   }
 
   // if there was no first higher measurement in the previous cycle,
   // no infertile pre-ovulatory phase may be assumed
   if (getTemperatureShift(previousCycle).detected && !cycle[0].mucus) {
     status.phases.preOvulatory = getPreOvulatoryPhase(cycle)
+    if (status.phases.preOvulatory.cycleDays.length === cycle.length) {
+      status.assumeFertility = false
+      return status
+    }
   }
 
+  status.phases.periOvulatory = {
+    start: { date: null },
+    cycleDays: []
+  }
   const periPhase = status.phases.periOvulatory
+
   if (status.phases.preOvulatory) {
     const prePhase = status.phases.preOvulatory
     periPhase.start.date = LocalDate.parse(prePhase.end.date).plusDays(1).toString()
diff --git a/test/sympto/fixtures.js b/test/sympto/fixtures.js
index 14d1eb2..159c055 100644
--- a/test/sympto/fixtures.js
+++ b/test/sympto/fixtures.js
@@ -83,10 +83,19 @@ const cycleWithoutAnyShifts = [
   { temperature: 36.45, mucus: 1 }
 ].map(convertToSymptoFormat)
 
+const fiveDayCycle = [
+  { temperature: 36.6, bleeding: 2 },
+  { temperature: 36.65 },
+  { temperature: 36.5 },
+  { temperature: 36.6 },
+  { temperature: 36.55 }
+].map(convertToSymptoFormat)
+
 export {
   cycleWithoutTempShift,
   cycleWithTempAndMucusShift,
   cycleWithTempAndNoMucusShift,
   cycleWithTempShift,
-  cycleWithoutAnyShifts
+  cycleWithoutAnyShifts,
+  fiveDayCycle
 }
\ No newline at end of file
diff --git a/test/sympto/index.spec.js b/test/sympto/index.spec.js
index e3cd067..b223629 100644
--- a/test/sympto/index.spec.js
+++ b/test/sympto/index.spec.js
@@ -1,7 +1,7 @@
 import chai from 'chai'
 import getSensiplanStatus from '../../lib/sympto'
 import {
-  cycleWithoutTempShift, cycleWithTempAndMucusShift, cycleWithTempAndNoMucusShift, cycleWithTempShift, cycleWithoutAnyShifts
+  cycleWithoutTempShift, cycleWithTempAndMucusShift, cycleWithTempAndNoMucusShift, cycleWithTempShift, cycleWithoutAnyShifts, fiveDayCycle
 } from './fixtures'
 
 const expect = chai.expect
@@ -52,6 +52,23 @@ describe('sympto', () => {
     })
   })
   describe('with previous higher measurement', () => {
+    describe('with no shifts detects pre-ovulatory phase', function () {
+      it('according to 5-day-rule', function () {
+        const status = getSensiplanStatus({
+          cycle: fiveDayCycle,
+          previousCycle: cycleWithTempShift
+        })
+
+        expect(Object.keys(status.phases).length).to.eql(1)
+        expect(status.assumeFertility).to.be.false()
+        expect(status.phases.preOvulatory).to.eql({
+          cycleDays: fiveDayCycle,
+          start: { date: '2018-06-01' },
+          end: { date: '2018-06-05' }
+        })
+      })
+
+    })
     describe('with no shifts detects pre- and peri-ovulatory phase', function () {
       it('according to 5-day-rule', function () {
         const status = getSensiplanStatus({