Due Date CalculatorDue Date Calculator

OnlineToken Usage:1 per callLatency:211ms avg

Due Date Calculator estimates pregnancy due dates using either last menstrual period or conception date, providing comprehensive pregnancy timeline information.

This API provides reliable and fast access to due date calculator data through a simple REST interface. Built for developers who need consistent, high-quality results with minimal setup time.

To use this API, you need an API key. You can get one by creating a free account and visiting your dashboard.

Endpoint

GET Request
GET https://api.apiverve.com/v1/duedatecalculator

Code Examples

Here are examples of how to call this API in different programming languages:

cURL Request
curl -X GET \
  "https://api.apiverve.com/v1/duedatecalculator?method=last_period&last_period=2024-01-01" \
  -H "X-API-Key: your_api_key_here"
JavaScript (Fetch API)
const response = await fetch('https://api.apiverve.com/v1/duedatecalculator?method=last_period&last_period=2024-01-01', {
  method: 'GET',
  headers: {
    'X-API-Key': 'your_api_key_here',
    'Content-Type': 'application/json'
  }
});

const data = await response.json();
console.log(data);
Python (Requests)
import requests

headers = {
    'X-API-Key': 'your_api_key_here',
    'Content-Type': 'application/json'
}

response = requests.get('https://api.apiverve.com/v1/duedatecalculator?method=last_period&last_period=2024-01-01', headers=headers)

data = response.json()
print(data)
Node.js (Native HTTPS)
const https = require('https');
const url = require('url');

const options = {
  method: 'GET',
  headers: {
    'X-API-Key': 'your_api_key_here',
    'Content-Type': 'application/json'
  }
};

const req = https.request('https://api.apiverve.com/v1/duedatecalculator?method=last_period&last_period=2024-01-01', options, (res) => {
  let data = '';
  res.on('data', (chunk) => data += chunk);
  res.on('end', () => console.log(JSON.parse(data)));
});

req.end();
PHP (cURL)
<?php

$ch = curl_init();

curl_setopt($ch, CURLOPT_URL, 'https://api.apiverve.com/v1/duedatecalculator?method=last_period&last_period=2024-01-01');
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_CUSTOMREQUEST, 'GET');
curl_setopt($ch, CURLOPT_HTTPHEADER, [
    'X-API-Key: your_api_key_here',
    'Content-Type: application/json'
]);

$response = curl_exec($ch);
curl_close($ch);

$data = json_decode($response, true);
print_r($data);

?>
Go (net/http)
package main

import (
    "fmt"
    "io"
    "net/http"

)

func main() {
    req, _ := http.NewRequest("GET", "https://api.apiverve.com/v1/duedatecalculator?method=last_period&last_period=2024-01-01", nil)

    req.Header.Set("X-API-Key", "your_api_key_here")
    req.Header.Set("Content-Type", "application/json")

    client := &http.Client{}
    resp, err := client.Do(req)
    if err != nil {
        panic(err)
    }
    defer resp.Body.Close()

    body, _ := io.ReadAll(resp.Body)
    fmt.Println(string(body))
}
Ruby (Net::HTTP)
require 'net/http'
require 'json'

uri = URI('https://api.apiverve.com/v1/duedatecalculator?method=last_period&last_period=2024-01-01')
http = Net::HTTP.new(uri.host, uri.port)
http.use_ssl = true

request = Net::HTTP::Get.new(uri)
request['X-API-Key'] = 'your_api_key_here'
request['Content-Type'] = 'application/json'

response = http.request(request)
puts JSON.pretty_generate(JSON.parse(response.body))
C# (HttpClient)
using System;
using System.Net.Http;
using System.Text;
using System.Threading.Tasks;

class Program
{
    static async Task Main(string[] args)
    {
        using var client = new HttpClient();
        client.DefaultRequestHeaders.Add("X-API-Key", "your_api_key_here");

        var response = await client.GetAsync("https://api.apiverve.com/v1/duedatecalculator?method=last_period&last_period=2024-01-01");
        response.EnsureSuccessStatusCode();

        var responseBody = await response.Content.ReadAsStringAsync();
        Console.WriteLine(responseBody);
    }
}

Authentication

This API requires authentication via API key. Include your API key in the request header:

Required Header
X-API-Key: your_api_key_here

Interactive API Playground

Test this API directly in your browser with live requests and responses.

Parameters

The following parameters are available for this API endpoint:

ParameterTypeRequiredLocationDescriptionExample
methodstringNoqueryCalculation method (last_period or conception_date)last_period
last_periodstringNoqueryFirst day of last period (YYYY-MM-DD) - for last_period method2024-01-01
conception_datestringNoqueryConception date (YYYY-MM-DD) - for conception_date method2024-01-15

Response

The API returns responses in JSON, XML, and YAML formats:

Example Responses

JSON Response
200 OK
{
  "status": "ok",
  "error": null,
  "data": {
    "calculation_method": "last_period",
    "last_period_date": "2024-01-01",
    "estimated_conception_date": "2024-01-15",
    "due_date": "2024-10-07",
    "current_progress": {
      "days_pregnant": 688,
      "weeks_pregnant": 98,
      "days_into_week": 2,
      "formatted": "98 weeks, 2 days",
      "trimester": 3,
      "percentage_complete": 245.71
    },
    "time_until_due": {
      "days": 0,
      "weeks": 0,
      "days_extra": 0,
      "formatted": "Past due date",
      "is_overdue": true
    },
    "upcoming_milestones": [],
    "important_dates": {
      "end_first_trimester": "2024-04-01",
      "end_second_trimester": "2024-07-08",
      "full_term_begins": "2024-09-16"
    },
    "disclaimer": "This is an estimate only. Due dates can vary. Consult your healthcare provider for medical advice."
  }
}
XML Response
200 OK
<Root>
  <status>ok</status>
  <error />
  <data>
    <calculation_method>last_period</calculation_method>
    <last_period_date>2024-01-01</last_period_date>
    <estimated_conception_date>2024-01-15</estimated_conception_date>
    <due_date>2024-10-07</due_date>
    <current_progress>
      <days_pregnant>688</days_pregnant>
      <weeks_pregnant>98</weeks_pregnant>
      <days_into_week>2</days_into_week>
      <formatted>98 weeks, 2 days</formatted>
      <trimester>3</trimester>
      <percentage_complete>245.71</percentage_complete>
    </current_progress>
    <time_until_due>
      <days>0</days>
      <weeks>0</weeks>
      <days_extra>0</days_extra>
      <formatted>Past due date</formatted>
      <is_overdue>true</is_overdue>
    </time_until_due>
    <important_dates>
      <end_first_trimester>2024-04-01</end_first_trimester>
      <end_second_trimester>2024-07-08</end_second_trimester>
      <full_term_begins>2024-09-16</full_term_begins>
    </important_dates>
    <disclaimer>This is an estimate only. Due dates can vary. Consult your healthcare provider for medical advice.</disclaimer>
  </data>
</Root>
YAML Response
200 OK
status: ok
error: 
data:
  calculation_method: last_period
  last_period_date: 2024-01-01
  estimated_conception_date: 2024-01-15
  due_date: 2024-10-07
  current_progress:
    days_pregnant: 688
    weeks_pregnant: 98
    days_into_week: 2
    formatted: 98 weeks, 2 days
    trimester: 3
    percentage_complete: 245.71
  time_until_due:
    days: 0
    weeks: 0
    days_extra: 0
    formatted: Past due date
    is_overdue: true
  upcoming_milestones: []
  important_dates:
    end_first_trimester: 2024-04-01
    end_second_trimester: 2024-07-08
    full_term_begins: 2024-09-16
  disclaimer: This is an estimate only. Due dates can vary. Consult your healthcare provider for medical advice.

Response Structure

All API responses follow a consistent structure with the following fields:

FieldTypeDescriptionExample
statusstringIndicates whether the request was successful ("ok") or failed ("error")ok
errorstring | nullContains error message if status is "error", otherwise nullnull
dataobject | nullContains the API response data if successful, otherwise null{...}

Response Data Fields

When the request is successful, the data object contains the following fields:

FieldTypeSample Value
calculation_methodstring"last_period"
last_period_datestring"2024-01-01"
estimated_conception_datestring"2024-01-15"
due_datestring"2024-10-07"
current_progressobject{...}
current_progress.days_pregnantnumber688
current_progress.weeks_pregnantnumber98
current_progress.days_into_weeknumber2
current_progress.formattedstring"98 weeks, 2 days"
current_progress.trimesternumber3
current_progress.percentage_completenumber245.71
time_until_dueobject{...}
time_until_due.daysnumber0
time_until_due.weeksnumber0
time_until_due.days_extranumber0
time_until_due.formattedstring"Past due date"
time_until_due.is_overduebooleantrue
upcoming_milestonesarray[]
important_datesobject{...}
important_dates.end_first_trimesterstring"2024-04-01"

Headers

Required and optional headers for API requests:

Header NameRequiredExample ValueDescription
X-API-KeyYesyour_api_key_hereYour APIVerve API key. Found in your dashboard under API Keys.
AcceptNoapplication/jsonSpecify response format: application/json (default), application/xml, or application/yaml
User-AgentNoMyApp/1.0Identifies your application for analytics and debugging purposes
X-Request-IDNoreq_123456789Custom request identifier for tracking and debugging requests
Cache-ControlNono-cacheControl caching behavior for the request and response

GraphQL AccessBETA

Most APIVerve APIs support GraphQL queries, allowing you to combine multiple API calls into a single request and retrieve only the data you need. This powerful feature enables you to orchestrate complex data fetching with precise field selection.

Not all APIs support GraphQL. Check the API schema or test in the GraphQL Explorer to confirm availability for this specific endpoint.

Token Cost: GraphQL requests cost 1 token for orchestration, plus the standard token cost for each API called in your query. For example, querying 3 APIs in a single GraphQL request would cost 1 + 3 = 4 tokens total.

GraphQL Endpoint
POST https://api.apiverve.com/v1/graphql
GraphQL Query Example
query {
  duedatecalculator(
    input: { method: "last_period", last_period: "2024-01-01", conception_date: "2024-01-15" }
  ) {
    calculation_method
    last_period_date
    estimated_conception_date
    due_date
    current_progress {
      days_pregnant
      weeks_pregnant
      days_into_week
      formatted
      trimester
      percentage_complete
    }
    time_until_due {
      days
      weeks
      days_extra
      formatted
      is_overdue
    }
    upcoming_milestones
    important_dates {
      end_first_trimester
      end_second_trimester
      full_term_begins
    }
    disclaimer
  }
}

Note: Authentication is handled via the x-api-key header in your GraphQL request, not as a query parameter.

CORS Support

All APIVerve APIs support Cross-Origin Resource Sharing (CORS) with wildcard configuration, allowing you to call the API directly from browser-based applications without proxy servers.

CORS HeaderValueDescription
Access-Control-Allow-Origin*Accepts requests from any origin
Access-Control-Allow-Methods*Accepts any HTTP method
Access-Control-Allow-Headers*Accepts any request headers

Browser Usage: You can make direct API calls from JavaScript running in the browser without encountering CORS errors. No additional configuration needed.

Rate Limiting

APIVerve implements rate limiting to ensure fair usage and maintain service quality across all users. Rate limits vary by subscription plan and are applied per API key.

PlanRate LimitDescription
Free5 requests/minHard rate limit enforced - exceeding will return 429 errors
StarterSmart LimitingProduction ready - performance-based throttling only as last resort
ProNo LimitProduction ready - no rate limiting or throttling
MegaNo LimitProduction ready - no rate limiting or throttling

Rate Limit Headers

When rate limits apply, each API response includes headers to help you track your usage:

HeaderDescription
X-RateLimit-LimitMaximum number of requests allowed per time window
X-RateLimit-RemainingNumber of requests remaining in the current window
X-RateLimit-ResetUnix timestamp when the rate limit window resets

Handling Rate Limits

Free Plan: When you exceed your rate limit, the API returns a 429 Too Many Requests status code. Your application should implement appropriate backoff logic to handle this gracefully.

Starter Plan: Smart limiting may slow down request processing during extreme load as a last resort, but will not return errors. All paid plans (Starter, Pro, Mega) are production-ready.

Pro & Mega Plans: No rate limiting or throttling applied.

Best Practices:

  • Monitor the rate limit headers to track your usage (Free plan only)
  • Implement caching where appropriate to reduce API calls
  • Upgrade to Pro or Mega for guaranteed no-throttle performance

Note: Rate limits are separate from token consumption. You may have tokens remaining but still hit rate limits on Free tier.

Client Libraries

To get started with minimal code, most of our APIs are available through client libraries and clients:

NPMPyPINuGetSwagger

Error Codes

The API uses standard HTTP status codes to indicate success or failure:

CodeMessageDescriptionSolution
200OKRequest successful, data returnedNo action needed - request was successful
400Bad RequestInvalid request parameters or malformed requestCheck required parameters and ensure values match expected formats
401UnauthorizedMissing or invalid API keyInclude x-api-key header with valid API key from dashboard
403ForbiddenAPI key lacks permission or insufficient tokensCheck token balance in dashboard or upgrade plan
429Too Many RequestsRate limit exceeded (Free: 5 req/min)Implement request throttling or upgrade to paid plan
500Internal Server ErrorServer error occurredRetry request after a few seconds, contact support if persists
503Service UnavailableAPI temporarily unavailableWait and retry, check status page for maintenance updates

Need help? Contact support with your X-Request-ID for assistance.

Frequently Asked Questions

How do I get an API key?
Sign up for a free account at dashboard.apiverve.com. Your API key will be automatically generated and available in your dashboard. The free plan includes 1,000 tokens plus a 500 token bonus.
What are tokens and how do they work?

Tokens are your API usage currency. Each successful API call consumes tokens based on the API's complexity. Most APIs cost 1 token per call, while more complex APIs may cost 2-5 tokens. Failed requests and errors don't consume tokens. Check the API details above to see the token cost for this specific API.

Can I use this API in production?

The free plan is for testing and development only. For production use, upgrade to a paid plan (Starter, Pro, or Mega) which includes commercial use rights, no attribution requirements, and guaranteed uptime SLAs. All paid plans are production-ready.

Can I use this API from a browser?
Yes! All APIVerve APIs support CORS with wildcard configuration, so you can call them directly from browser-based JavaScript without needing a proxy server. See the CORS section above for details.
What happens if I exceed my token limit?

When you reach your monthly token limit, API requests will return an error until you upgrade your plan or wait for the next billing cycle. You'll receive notifications at 80% and 95% usage to give you time to upgrade if needed.

What's Next?

Continue your journey with these recommended resources

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