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CompletedNCT04703270periCOVIDUpdated Jun 18, 2025Results posted

Understanding COVID-19 Infection in Pregnant Women and Their Babies

An observational study in Corona Virus Infection, Pregnancy Related and Neonatal Infection, sponsored by St George's, University of London. Completed at 1 site in United Kingdom. Open to female participants aged 18 Years and older, including healthy volunteers. Per ClinicalTrials.gov, last updated 2025-06-18.

Sponsored by St George's, University of London · Observational

Study type
Observational
Model
Case-control
Time perspective
Prospective
Enrollment
881
Ages
18 Years and older
Sex
Female
01

Study summary

This national study will recruit expectant mothers with and without positive nasopharyngeal swabs for SARS-CoV-2, and aims to determine the seroepidemiology of SARS-CoV-2 amongst expectant mothers and their infants in the U.K.

02

Conditions studied

  • Corona Virus Infection
  • Pregnancy Related
  • Neonatal Infection
  • Breastfeeding
03

In context

Infections

6,687 studies on the registry are indexed under Infections; 807 are open to participants now.

This study's enrollment of 881 is above the median of 240 across 2,136 observational studies indexed under Infections.

Browse Infections studies →

Lead sponsor

St George's, University of London is the lead sponsor of 105 studies on the registry; 11 are open to participants now.

Counted across the registry records on this site, refreshed daily.

04

Who can participate

Ages eligible
18 Years and older
Sexes eligible
Female
Accepts healthy volunteers
Yes
Sampling method
Non-probability sample

Study population

All pregnant women ≥ 24 weeks gestation in England.

Inclusion criteria

  • Signed informed consent form
  • Any woman pregnant in selected hospitals in England who has no signs or symptoms of COVID-19 disease during pregnancy and is rtPCR negative at delivery
  • Any woman pregnant in any hospital in England who tests positive by rtPCR at any point during pregnancy from 24 weeks gestation onwards, regardless of signs and symptoms

Exclusion criteria

Exclusion Criteria:

  • If the pregnant woman is under 18 years in prison or unable to make an informed consent for other reasons (e.g. learning difficulties, language barriers)
05

Study design

Observational model
Case-control
Time perspective
Prospective
Enrollment
881 participants (actual)
Patient registry
No

Groups and cohorts

  • Exposed

    Expectant mothers with a positive nasopharyngeal swab for SARS-CoV-2 at any point during pregnancy from 24 weeks gestation regardless of antibody status.

  • Seropositive

    Expectant mothers with a negative nasopharyngeal swab for SARS-CoV-2 at any point during pregnancy from 24 weeks gestation but positive IgM/IgG antibodies against SARS-CoV-2.

  • Unexposed

    Expectant mothers with a negative nasopharyngeal swab for SARS-CoV-2 at any point during pregnancy from 24 weeks gestation and negative IgM/IgG antibodies against SARS-CoV-2.

06

What researchers measure

Primary outcomes

  1. Antibody Concentrations in Maternal Blood in Pregnant Women in England

    Antibody concentrations in maternal blood in pregnant women in England: ADCD-S values reported

    Time frame: Delivery

  2. Antibody Concentrations in Cord/Infant Blood at Delivery

    Cord blood was tested to determine infant antibody levels; where a cord blood sample was not available, a blood sample was taken from the infant instead. ADCD-S assay results are presented.

    Time frame: Delivery

Secondary outcomes

  1. Number of Participants With Breastmilk Samples Positive for Antibodies Specific to SARS-CoV-2

    Number of participants with breastmilk samples positive for antibodies specific to SARS-CoV-2

    Time frame: At birth

  2. Number of Mother-infant Pairs Who Are Both rtPCR Positive for SARS-CoV-2 in Blood at Delivery

    Time frame: Delivery

  3. Number of Mother-infant Pairs Who Are Both rtPCR Positive for SARS-CoV-2 in Secretions at Delivery

    Time frame: Delivery

  4. Breastmilk Samples That Are rtPCR Positive

    Time frame: Delivery

  5. Placental Samples That Are rtPCR Positive

    Time frame: Delivery

  6. Number of Participants in Whose Placental Sample the Virus Can be Grown in Vitro

    Time frame: Delivery

  7. Number of Participants in Whose Breast Milk Sample the Virus Can be Grown in Vitro

    Time frame: Delivery

  8. Number of Mother-baby Pairs in Whom the Virus Can be Grown in Vitro

    Time frame: 6 weeks post delivery

07

Results

Posted Jun 18, 2025

Participant flow

Participant flow — Overall Study
MilestoneExposedUnexposedVaccinatedVaccinated and Exposed
Started1736274338
Completed1736274338
Not completed0000

Outcome measures

PrimaryAntibody Concentrations in Maternal Blood in Pregnant Women in England

Antibody concentrations in maternal blood in pregnant women in England: ADCD-S values reported

Time frame:
Delivery
Reported as:
Geometric mean · CAU/ml
Antibody Concentrations in Maternal Blood in Pregnant Women in England
CAU/mlExposedUnexposedVaccinatedVaccinated and Exposed
Antibody Concentrations in Maternal Blood in Pregnant Women in England37.2 (13.2 to 102.1)7.2 (5.0 to 5.0)80.3 (31.9 to 228.3)590.5 (308.7 to 1094.8)
PrimaryAntibody Concentrations in Cord/Infant Blood at Delivery

Cord blood was tested to determine infant antibody levels; where a cord blood sample was not available, a blood sample was taken from the infant instead. ADCD-S assay results are presented.

Time frame:
Delivery
Reported as:
Geometric mean · CAU/mL
Antibody Concentrations in Cord/Infant Blood at Delivery
CAU/mLExposedUnexposedVaccinatedVaccinated and Exposed
Antibody Concentrations in Cord/Infant Blood at Delivery35.9 (11.7 to 88.4)7.5 (5.0 to 5.0)83.9 (29.8 to 227.8)549.0 (323.9 to 1314.7)
SecondaryNumber of Participants With Breastmilk Samples Positive for Antibodies Specific to SARS-CoV-2

Number of participants with breastmilk samples positive for antibodies specific to SARS-CoV-2

Time frame:
At birth
Reported as:
Count of participants · Participants
Number of Participants With Breastmilk Samples Positive for Antibodies Specific to SARS-CoV-2
ParticipantsExposedUnexposedVaccinatedVaccinated and Exposed
Number of Participants With Breastmilk Samples Positive for Antibodies Specific to SARS-CoV-2—0160
SecondaryNumber of Mother-infant Pairs Who Are Both rtPCR Positive for SARS-CoV-2 in Blood at Delivery
Time frame:
Delivery

No measurements were reported for this outcome.

SecondaryNumber of Mother-infant Pairs Who Are Both rtPCR Positive for SARS-CoV-2 in Secretions at Delivery
Time frame:
Delivery
Reported as:
Number · Number of mother-infant pairs
Number of Mother-infant Pairs Who Are Both rtPCR Positive for SARS-CoV-2 in Secretions at Delivery
Number of mother-infant pairsExposedVaccinatedVaccinated and Exposed
Number of Mother-infant Pairs Who Are Both rtPCR Positive for SARS-CoV-2 in Secretions at Delivery000
SecondaryBreastmilk Samples That Are rtPCR Positive
Time frame:
Delivery

No measurements were reported for this outcome.

SecondaryPlacental Samples That Are rtPCR Positive
Time frame:
Delivery
Reported as:
Number · No. of Placental Samples rtPCR positive
Placental Samples That Are rtPCR Positive
No. of Placental Samples rtPCR positiveExposedVaccinated and Exposed
Placental Samples That Are rtPCR Positive10
SecondaryNumber of Participants in Whose Placental Sample the Virus Can be Grown in Vitro
Time frame:
Delivery

No measurements were reported for this outcome.

SecondaryNumber of Participants in Whose Breast Milk Sample the Virus Can be Grown in Vitro
Time frame:
Delivery

No measurements were reported for this outcome.

SecondaryNumber of Mother-baby Pairs in Whom the Virus Can be Grown in Vitro
Time frame:
6 weeks post delivery

No measurements were reported for this outcome.

Adverse events

Collected over Over the study period, i.e. until 6 weeks postpartum.. Non-serious events are listed at a 0% frequency threshold.

Adverse event summary by group
GroupDeathsSeriousOther
Exposed0/173 (0%)0/173 (0%)0/173 (0%)
Unexposed0/627 (0%)0/627 (0%)0/627 (0%)
Vaccinated0/43 (0%)0/43 (0%)0/43 (0%)
Vaccinated and Exposed0/38 (0%)0/38 (0%)0/38 (0%)

Baseline characteristics

Age, Continuous
Age, Continuous(years)ExposedUnexposedVaccinatedVaccinated and ExposedTotal
Median33.0 (29.0 to 36.0)31.0 (27.0 to 35.0)34.0 (30.5 to 37.0)33.5 (31.3 to 36.8)32.0 (28.0 to 32.0)
Sex: Female, Male
Sex: Female, Male(Participants)ExposedUnexposedVaccinatedVaccinated and ExposedTotal
Female1736274338881
Male00000
Race/Ethnicity, Customized
Race/Ethnicity, Customized(Participants)ExposedUnexposedVaccinatedVaccinated and ExposedTotal
White854963224637
Asian/Asian British9548475
Black African/Caribbean/British4200024
Other8122123
Mixed/Multiple1120013
Not Stated663319109
08

Study locations

1 site
  • St George's, University of London
    London, SW17 0RE, United Kingdom
09

References and documents

Study documents

  • Protocol and statistical analysis plan · Nov 17, 2020

Documents are hosted by the registry — open the source record to download them.

Individual participant data

Plan to share: No

10

Updates

Tracking since Sep 25, 2026
No changes since tracking began. The registry record was last updated on Jun 18, 2025, before this site started recording changes on Sep 25, 2026. Its history is on ClinicalTrials.gov ↗
11

Registry details

Key details

Study ID
NCT04703270
Lead sponsor
St George's, University of London
Responsible party
Sponsor
First posted
Jan 11, 2021
Start date
Jan 4, 2021
Primary completion
Apr 30, 2022
Completion
Sep 30, 2023
Results posted
Jun 18, 2025
Last update
Jun 18, 2025

Oversight

FDA-regulated drug
No
FDA-regulated device
No
View the source record on ClinicalTrials.gov ↗

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This study is completed, as verified in Aug 2024. You cannot join it, but the record below documents what was studied.

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