Time to pregnancy recognition among users of an FDA-cleared fertility application

Figures & data

Table 1. Summary of the literature investigating time to pregnancy detection.

Paper	#participants	location	sampling date	sample	Timing/ definition of pregnancy detection
(Ayoola 2015)	143,303	29 US states	2000–2004	live births within 2 to 6 months before being contacted	Self-reported survey of women that had had a live birth 2–6 months before being contacted. Participants were asked whe n they were ‘sure’ they were pregnant (pregnancy test or nurse/doctor visit), which is analysed as pregnancy ‘recognition’.
(Branum and Ahrens 2017)	17,406	US	1995–2013	at least one pregnancy in the 4 or 5 years prior to interview that did not result in induced abortion or adoption	Self-reported timing of pregnancy ‘awareness’ in a national survey asking women about past pregnancies.
(Finer et al.2006)	1209	US	2004	abortion patients at 11 large providers	In-clinic questionnaire. Self-reported pregnancy ‘suspicion’, pregnancy test timing.
(Foster et al.2021)	956	US	2008–2010	abortion patients at 30 abortion facilities contacted 1 week after either receiving or being denied an abortion	Telephone interviews. Participants were asked when they first discovered they were pregnant, which is analysed as pregnancy ‘recognition’ or ‘discovery’ used interchangeably.
(Finer et al.2006, McCarthy et al.2018)	458	Utah	2013–2014	abortion patients at 4 family planning facilities	Self-reported state-mandated survey from abortion information visit patients are required to complete prior to an abortion. Pregnancy ‘discovery’.
(Ralph et al.2022)	259	6 US states	2016–2017	visitors to reproduction clinics for mixed reasons (34% for abortion, 25% for prenatal care, 31% for pregnancy tests)	In-clinic questionnaire. Self-reported pregnancy ‘suspicion’, home test timing or ‘confirmation’ and clinic visit.
(Swanson et al.2014)	592	6 US states	2010	abortion patients at 6 large abortion clinics	In-clinic computer questionnaire. Participants were asked when they took their first pregnancy test, which was gauged against gestational age at time of visit evaluated by ultrasound, which is analysed as pregnancy ‘recognition’.

Figure 1. Selection of pregnancies on the Natural Cycles application.

Table 2. Demographic characteristics: distribution of the pregnancies (n = 23728) and stratified mean time from the last menstrual period to the first positive pregnancy test (NC° Plan Pregnancy vs NC° Birth Control).

Sociodemographic variable	distribution within the dataset – number, percentage of total	LMP to pregnancy test [days] – mean (with 95% confidence interval)		LMP to pregnancy test > = 6 weeks – percentage of total
		NC° Plan Pregnancy	NC° Birth Control	NC° Plan Pregnancy	NC° Birth Control
Age at the start of the conception cycle
18–24	3111 (13.11%)	31.8 (95% CI: 31.2–32.4)	36.9 (95% CI: 35.9–37.8)	8.7%	18.1%
25–29	9423 (39.71%)	31.4 (95% CI: 31.1-31.7)	35.9 (95% CI: 35.3-36.5)	6.9%	15.8%
30–34	8518 (35.90%)	31.2 (95% CI: 31.0–31.5)	35.5 (95% CI: 34.7–36.2)	6.3%	14.6%
35–39	2373 (10.00%)	30.8 (95% CI: 30.3–31.3)	35.2 (95% CI: 33.6–36.7)	4.6%	13.0%
40–45	303 (1.28%)	30.6 (95% CI: 29.3–32.0)	32.8 (95% CI: 31.3–34.3)	4.8%	10.5%
Body mass index
0–18.5	309 (1.30%)	32.6 (95% CI: 31.2–34.1)	39.2 (95% CI: 33.9–44.4)	8.5%	23.3%
18.5–25	8015 (33.78%)	31.0 (95% CI: 30.7–31.3)	35.3 (95% CI: 34.8–35.9)	5.7%	15.8%
25–30	3567 (15.03%)	30.8 (95% CI: 30.4–31.2)	34.9 (95% CI: 34.1–35.8)	6.0%	13.9%
>30	2095 (8.83%)	31.6 (95% CI: 31.0–32.2)	37.6 (95% CI: 35.7–39.5)	7.6%	16.7%
None	9742 (41.06%)
Race/ethnicity
Black or African American or African	224 (0.94%)	32.0 (95% CI: 29.1–35.0)	35.1 (95% CI: 33.1–37.2)	5.4%	13.2%
Hispanic/Latina	562 (2.37%)	32.3 (95% CI: 31.1–33.5)	34.4 (95% CI: 32.3–36.5)	10.5%	16.1%
Non-Hispanic White	5256 (22.15%)	31.0 (95% CI: 30.7–31.3)	34.8 (95% CI: 34.1–35.6)	5.8%	13.0%
Middle Eastern or North African	17 (0.07%)	28.2 (95% CI: 25.9–30.5)	32.5 (95% CI: 28.1–36.9)	0.0%	0.0%
Central Asian	6 (0.03%)	34.0 (95% CI: 29.6–38.4)	–	0.0%	0.0%
South Asian	25 (0.11%)	33.3 (95% CI: 29.9–36.7)	–	12.5%	0.0%
Southeast Asian	49 (0.21%)	32.2 (95% CI: 27.6–36.8)	35.6 (95% CI: 32.7–38.5)	3.0%	12.5%
East Asian	41 (0.17%)	31.6 (95% CI: 29.5–33.6)	51.8 (95% CI: 13.5–90.1)	9.4%	11.1%
Native Hawaiian or Other Pacific Islander	22 (0.09%)	33.4 (95% CI: 29.2–37.7)	36.7 (95% CI: 30.4–42.9)	15.8%	33.3%
American Indian or Alaska Native or First Peoples or Indigenous or Aboriginal	33 (0.14%)	29.2 (95% CI: 27.8–30.7)	31.3 (95% CI: 28.1–34.6)	0.0%	0.0%
Other	172 (0.72%)	31.2 (95% CI: 30.1–32.2)	33.6 (95% CI: 32.1–35.0)	2.8%	9.4%
None	17321 (73.00%)
Age of the youngest child living at home
0–12 months	1495 (6.30%)	30.9 (95% CI: 30.4–31.4)	35.9 (95% CI: 34.2–37.7)	5.1%	16.1%
1–3 years	1214 (5.12%)	30.4 (95% CI: 30.0–30.8)	33.9 (95% CI: 32.7–35.1)	5.2%	12.1%
3–6 years	223 (0.94%)	30.6 (95% CI: 28.7–32.6)	33.1 (95% CI: 31.9–34.3)	5.1%	5.7%
Older than 6 years	186 (0.78%)	31.3 (95% CI: 29.1–33.5)	32.6 (95% CI: 31.0–34.1)	7.1%	9.6%
I don’t have children living at home	3848 (16.22%)	31.2 (95% CI: 30.9–31.6)	34.6 (95% CI: 34.0–35.3)	6.5%	12.9%
None	16762 (70.64%)
Parity, number of previous pregnancies
No, never	6305 (26.57%)	31.7 (95% CI: 31.5–32.0)	36.4 (95% CI: 35.7–37.2)	8.1%	17.0%
Yes, once	1873 (7.89%)	30.9 (95% CI: 30.3–31.5)	35.7 (95% CI: 34.3–37.1)	6.0%	16.3%
Yes, twice	701 (2.95%)	31.0 (95% CI: 30.1–31.9)	34.3 (95% CI: 32.6–36.0)	5.7%	11.8%
Yes, 3 times or more	575 (2.42%)	31.0 (95% CI: 29.4–32.5)	32.6 (95% CI: 31.6–33.7)	4.7%	10.8%
None	14274 (60.16%)
Highest education level
Elementary school	13 (0.05%)	27.9 (95% CI: 26.5–29.2)	31.3 (95% CI: 27.8–34.8)	0.0%	0.0%
High school degree	905 (3.81%)	32.3 (95% CI: 31.2–33.3)	36.2 (95% CI: 34.6–37.8)	7.5%	14.0%
Trade/technical/vocational training	856 (3.61%)	32.0 (95% CI: 30.8–33.1)	35.9 (95% CI: 34.5–37.3)	7.6%	17.4%
University degree	9928 (41.84%)	31.2 (95% CI: 30.9–31.4)	35.2 (95% CI: 34.6–35.7)	6.2%	14.9%
PhD	752 (3.17%)	31.3 (95% CI: 30.3–32.4)	39.0 (95% CI: 34.8–43.2)	4.5%	17.1%
None	11274 (47.51%)
Relationship status
In a relationship	187 (0.79%)	31.2 (95% CI: 29.6–32.9)	33.0 (95% CI: 32.0–34.1)	0.0%	10.4%
Engaged or married	3176 (13.39%)	30.7 (95% CI: 30.3–31.1)	34.8 (95% CI: 34.2–35.4)	4.6%	13.6%
It’s complicated	36 (0.15%)	28.3 (95% CI: 18.7–38.0)	34.4 (95% CI: 30.2–38.6)	0.0%	12.1%
Single	49 (0.21%)	27.0 (95% CI: 22.9–31.1)	34.5 (95% CI: 31.6–37.5)	0.0%	6.5%
None	20280 (85.47%)
Average cycle length prior to conception
<20	82 (0.35%)	31.8 (95% CI: 29.1–34.6)	37.8 (95% CI: 30.6–45.0)	13.7%	19.4%
>20-25	1184 (4.99%)	27.9 (95% CI: 27.3–28.5)	34.6 (95% CI: 32.4–36.7)	3.1%	11.7%
>25-30	12495 (52.66%)	29.3 (95% CI: 29.1–29.5)	33.4 (95% CI: 32.9–33.8)	2.5%	8.7%
>30-35	7099 (29.92%)	32.8 (95% CI: 32.5–33.1)	37.4 (95% CI: 36.7–38.0)	7.2%	19.6%
>35-40	1705 (7.19%)	36.5 (95% CI: 35.9–37.0)	42.8 (95% CI: 41.2–44.5)	20.9%	40.0%
>40	317 (1.34%)	41.5 (95% CI: 39.3–43.6)	43.1 (95% CI: 40.3–45.9)	38.9%	48.2%
None	846 (3.57%)
Variation in cycle length prior to conception
<5	17644 (74.36%)	30.5 (95% CI: 30.3–30.6)	34.6 (95% CI: 34.2–34.9)	4.4%	12.5%
≥5	3038 (12.80%)	33.8 (95% CI: 33.3–34.3)	38.0 (95% CI: 36.8–39.2)	13.1%	23.9%
None	3046 (12.84%)

Figure 2. Mean time from last menstrual period to first positive pregnancy test: NC° Plan Pregnancy vs NC° Birth Control.

Table 3. Time to pregnancy confirmation (days from the first day of the last menstrual period to the first positive pregnancy test), average and right tail of the distribution: NC° Plan Pregnancy vs NC° Birth Control.

	LMP to pregnancy test [days] – mean (with 95% confidence interval)			LMP to pregnancy test ≥6 weeks – percentage of total			LMP to pregnancy test ≥7 weeks – percentage of total
	NC° Plan Pregnancy	NC° Birth Control	statistical p value	NC° Plan Pregnancy	NC° Birth Control	statistical p value	NC° Plan Pregnancy	NC° Birth Control	statistical p value
main analytical population - no conditions	31.3 (95% CI: 31.1–31.5)	35.9 (95% CI: 35.5–36.3)	WT <0.001 MWU = <0.001	6.5%	15.7%	Z < 0.001	3.0%	7.6%	Z < 0.001
tracking regularly − 10+ basal body temperatures tracked before the 30th day of the conception cycle	30.6 (95% CI: 30.5–30.7)	34.2 (95% CI: 33.9– 34.5)	WT <0.001 MWU <0.001	5.6%	13.1%	Z < 0.001	2.1%	5.6%	Z < 0.001
statistical p value- between main analytical population and tracking regularly	WT <0.001 MWU = 0.004	WT <0.001 MWU = 0.02		Z < 0.001	Z < 0.001		Z < 0.001	Z < 0.001

The statistical p values for comparisons are given for the two-tailed Welch’s T-tests (WT), the Mann–Whitney U-tests (MWU) or the two-tailed Z-test (Z).

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Data availability statement

Data is available upon reasonable request to the corresponding author.