Provisional Estimates for Selected Maternal and Infant Outcomes by Month, 2018-2020
The table below presents provisional estimates for selected pregnancy characteristics and birth outcomes that may be relevant to the direct and indirect impacts of COVID-19. Estimates are shown for each month in 2020 and compared with data for the same period in 2019 and 2018 to identify changes. Note that COVID-19 would have had little to no impact on many of these indicators in the early months of the pandemic.
|Characteristic||Month of Birth|
|Initiation of prenatal care|
|Prenatal care beginning in the 1st trimester|
|Late or no prenatal care3|
|Adequacy of prenatal care utilization5|
|Less than adequate8|
|Cesarean delivery (total)|
|Low-risk cesarean delivery10|
|Very low birthweight15|
1Provisional 2020 data; based on 99.94% of births. See Technical Notes.
2Significant increasing trend by year (p < 0.05).
3Prenatal care the began in the third trimester and no prenatal care.
4Significant quadratic trend by year (p < 0.05).
5Based on the Adequacy of Prenatal Care Utilization Index. See references 1 and 2.
6Prenatal care beginning by the fourth month of pregnancy and including 110% or more of the recommended number of visits.
7Prenatal care beginning by the fourth month of pregnancy and including at least 80%-109% of the recommended number of visits.
8Prenatal care beginning after the fourth month of pregnancy or including less than 50% of the recommended number of visits.
9Significant decreasing trend by year (p < 0.05).
10Low-risk cesarean rate is the number of singleton, term (37 or more weeks of gestation based on the obstetric estimate), cephalic, cesarean deliveries to women having a first birth per 100 women delivering singleton, term, cephalic births. For more information on method of delivery, see reference 3.
11Born prior to 37 completed weeks of gestation based on the obstetric estimate. For more information on obstetric estimate, see reference 3.
12Born prior to 34 completed weeks of gestation based on the obstetric estimate. For more information on obstetric estimate, see reference 3.
13Born between 34 and 36 completed weeks of gestation based on the obstetric estimate. For more information on obstetric estimate, see reference 3.
14Less than 2,500 grams.
15Less than 1,500 grams.
SOURCE: National Center for Health Statistics, National Vital Statistics System, Natality.
The National Center for Health Statistics (NCHS) is monitoring the potential impact of Coronavirus Disease 2019 (COVID-19) on pregnant women and newborn infants through compilation of the most recent birth data available through the National Vital Statistics System. Provisional estimates of selected pregnancy characteristics and birth outcomes are shown for each month in 2020 along with the same period in 2019 and 2018 to identify changes that could potentially be associated with the indirect and direct impacts of COVID-19. These provisional estimates may be revised as additional and updated birth records are received. Note that the COVID-19 pandemic could have little if any impact on indicators such as the number of births and the percentage of women with first trimester prenatal care for births occurring in the early months of the pandemic.
Nature and sources of data
Provisional estimates are based on all complete birth records received and processed by NCHS as of a specified cutoff date. National provisional estimates include events occurring to U.S. residents within the 50 states and District of Columbia. NCHS receives the birth records and monthly provisional occurrence counts from state vital registration systems through the Vital Statistics Cooperative Program.
Provisional data are based on monthly birth records received from the states. When monthly total record counts for a state do not appear to be complete based on a comparison with counts from the same month of the previous year, individual records are weighted to an expected count of births for that period.
Table I shows the percent completeness of the provisional data by month for the United States and each jurisdiction based on where the births occurred. Where the total number of records received by a state by month is not complete, the percent completeness is obtained by dividing the number of complete records from each state for each month by the corresponding expected count and multiplying by 100. Expected counts are estimated by examining trends in corresponding data over the previous three-year period to adjust the counts by state and month. If the number of complete records is greater than the expected count, the state-specific number of complete records is used instead, and the weight is set at 1. These monthly state-specific expected counts serve as control totals and are the basis for the record weights used for computing the monthly estimates. The record weights are calculated by taking the inverse of the percent completeness (divided by 100) by state and month. Although data by place of occurrence are used to compute the weights, all rate estimates are for the residents of the 50 states and District of Columbia.
|District of Columbia||99.9||99.9||99.9||99.9||99.9||99.9|
|New York State1||100||99.9||99.9||99.9||99.9||99.7|
|New York City||100||100||99.9||100||99.8||99.6|
1 Excludes New York City.
NOTE: The percent completeness is obtained by dividing the number of complete records from each state for each month by the expected count and multiplying by 100. NCHS receives the birth records and monthly provisional occurrence counts from state vital registration systems through the Vital Statistics Cooperative Program.
Rates are presented as per 100 births.
Accuracy of estimates
Provisional estimates are subject to some nonrandom sampling error. The monthly provisional estimates are based on data that are potentially more incomplete for the most recent months. Where data are weighted to an expected count of births, no imputations are performed, because it is assumed that the data are missing at random (i.e., the degree of missing data is unrelated to estimates of reproductive health). Estimates of completion rates by month were all above 95% for the United States. However, certain states may have more delayed reporting, and it is unknown whether indicators of reproductive health may be different for these states compared with states having complete reporting.
Estimates for previously released months are revised based on new data and updates received since the previous release. As a result, the reliability of estimates for a specific month will improve with each release and estimates for previous months may change with the addition of updated data.
Interpretation of changes over time
Statistical significance of trends in percentages by month was assessed using the Cochran-Armitage test, a modified chi squared test, at the 0.05 level, and indicated in the table.
Adequacy of Prenatal Care Utilization Index
The Adequacy of Prenatal Care Utilization Index (APNCU) is based on the month prenatal care began and the number of visits adjusted for gestational age (1). The number of visits is assessed by comparing the number of reported visits with the number of expected visits for a particular gestational age, based on recommendations from ACOG (1,2). Inadequate care is defined as all prenatal care that began after the fourth month of pregnancy, as well as prenatal care that included less than 50% of the recommended number of visits. Intermediate care is defined as care that began by the fourth month of pregnancy and includes 50%-79% of the recommended visits. Adequate care is defined as care that began by the fourth month and includes 80%-109% of the recommended visits. Adequate plus care is defined as care that began by the fourth month and includes 110% or more of the recommended visits. In this table, “inadequate” and “intermediate” care are combined for the category “less than adequate” care (1,2). For detailed information on other measures shown in Table, see reference 3.
- Kotelchuck M. An evaluation of the Kessner Adequacy of Prenatal Care Index and a proposed Adequacy of Prenatal Care Utilization Index. Am J Public Heath 84(9):1414-20.1994.
- Osterman MJK, Martin JA. Timing and adequacy of prenatal care in the United States, 2016 pdf icon[PDF – 359 KB]. National Vital Statistics Reports, vol 67 no 3. Hyattsville, MD: National Center for Health Statistics. 2018.
- National Center for Health Statistics. User Guide to the 2018 natality public use file. Hyattsville, MD.