Many beginners set eggs with excitement, only to discover that some embryos stop developing midway. While frustrating, most losses have identifiable causes. This guide follows a clear progression—from diagnosis by stage, to specific fixes, to a monitoring schedule you can apply next set—so your improvements feel logical instead of trial and error. For setup fundamentals, review our egg incubator setup guide first.
Normal vs. Concerning Losses
Some embryo loss is normal. Across small-flock conditions, overall hatchability commonly ranges from 50–85%. With consistent management, aiming for 70–85% is realistic for many home incubators. Don’t chase perfection; chase repeatable processes.
Before You Start: Eggs, Storage, and Baselines
Egg Selection & Storage
Choose clean, intact eggs of normal shape and size from healthy flocks. For storage, keep fertile eggs at 55–60°F (13–16°C) and 70–75% RH, pointy-end down, and set within 7 days when possible. Avoid rapid temperature swings and sweating. If you are new to incubation, start with our first-timers guide to hatching.
Incubator Baselines (forced-air)
- Temperature: Target 99.5°F (37.5°C) and keep within 99.5–100°F.
- Humidity: Day 1–18 at 50–55% RH; raise to 65–70% RH at lockdown (Day 18). See practical moisture checks in our candling fertile eggs timeline.
- Turning: At least 3×/day, ideally 5×/day; auto-turners may turn hourly.
Early-Stage Death (Days 0–7): Diagnose & Fix
Day-7 candling should reveal strong veins and a dark embryo. If the egg is clear or shows a blood ring, address the most likely causes below.
| Likely Cause | What You’ll See | Action |
|---|---|---|
| Infertility / weak fertility | Clear at Day 7; no veins | Source from proven breeding flocks; maintain breeder health and nutrition |
| Poor storage | Weak/no development; mixed clears | Hold at 55–60°F, 70–75% RH; set within 7 days; avoid temp shocks |
| Early temperature error | Uniform early deaths | Stabilize incubator pre-set; verify 99.5–100°F with a calibrated backup thermometer |
| Contamination | Blood rings; odor | Sanitize equipment; remove cracked/dirty/leaking eggs promptly |
Mid-Incubation Death (Days 8–14)
At mid-stage, turning regularity and humidity stability are decisive. Inconsistency often shows up as arrested development without clear malformations. If you’re unsure what normal looks like under light, compare with our candling visuals and timeline.
- Turning: Maintain even, frequent turns (≥3×/day; 5×/day preferred) to prevent adhesion and malposition.
- Humidity: Hold 50–55% RH; large swings shrink or overfill the air cell and impair gas exchange.
- Hygiene: Remove leaking eggs immediately; wipe trays; avoid handling with dirty or wet hands.
Late-Stage Death (Days 15–21 / Lockdown to Hatch)
Late losses are often environmental: ventilation, temperature stability, and correct positioning during lockdown.
| Cause | Signs | Prevention |
|---|---|---|
| Insufficient ventilation | Fully formed chicks dead in shell; small air cells | Ensure open vents and unobstructed airflow; avoid overcrowding; see incubator setup tips |
| Overheating / chilling | Clustered late deaths after spikes/drops | Confirm calibration; stabilize the room; avoid opening during hatch |
| Malposition | Beak not at air cell; failure to pip | Set pointy-end down; stop turning at Day 18 |
| Shell defects | “Stuck” chicks | Improve breeder nutrition; avoid overly thin/thick or washed shells |
The Lockdown Period, Clearly Explained
Begin lockdown on Day 18. Stop turning, increase humidity to 65–70% RH, open vents fully, and avoid opening the incubator. Chicks position for hatch and rely on higher ambient humidity to keep membranes pliable while pipping and zipping. For a prevention-first walkthrough, see our first-timers guide to hatching.
What to Look For When Candling
| Checkpoint | Normal | Warning Signs |
|---|---|---|
| Day 7 | Spider-like veins; dark embryo spot | Clear (infertile/very early death); blood ring; leaks — candling fertile eggs guide |
| Day 14 | Large dark mass; active movement; defined air cell | No growth since Day 7; detached/saddle air cell; foul odor |
| Day 18 (pre-lockdown) | Prominent air cell; embryo fills shell | Tiny air cell (humidity too high); very large air cell (too low) |
Troubleshooting Decision Tree
Early deaths (Day 0–7) → Check fertility & storage → Verify 99.5–100°F → Sanitize & remove problem eggs.
Mid deaths (Day 8–14) → Confirm turning ≥3–5×/day → Hold 50–55% RH → Improve hygiene and remove leakers.
Late deaths (Day 15–21) → Open vents & stabilize temp → Lockdown 65–70% RH → Ensure eggs set pointy-end down and stop turning.
Monitoring Schedule You Can Copy
| When | Check | Target |
|---|---|---|
| Daily, morning & evening | Temperature & humidity log | 99.5–100°F; 50–55% RH (lockdown 65–70%) |
| Every day (Day 1–17) | Turning | ≥3×/day, ideally 5×/day (auto-turners hourly) |
| Day 7 & Day 14 | Candling | Remove clears, blood rings, leakers — use candling timeline |
| Weekly | Sensor calibration cross-check | Backup thermometer/hygrometer |
| Day 18 | Lockdown setup | Stop turning; 65–70% RH; open vents; follow incubator setup guide |
Power & Calibration Safeguards
- Power: Prepare a backup plan; even short outages can cause synchronized losses. Consider an auto-turn, dual-power incubator if outages are common.
- Calibration: Cheap sensors drift—verify with a trusted secondary device weekly.
- Airflow: Keep vents/fans unobstructed; avoid lining that blocks circulation; review airflow and placement tips.
Next Steps & Resources
- Candling fertile eggs timeline
- First-timers guide to hatching
- Incubator setup guide
- Chick care in the first 24 hours
- Auto-turn & dual-power incubators
FAQ
How often should I turn chicken eggs?
Turn at least 3 times daily; 5 times is better. Auto-turners often rotate hourly, which helps prevent adhesion and malposition.
When should I candle eggs?
Day 7 and Day 14 are the most helpful checkpoints. Remove clears, blood rings, and leaking eggs to protect the rest. For photos and timing, see our candling guide.
What humidity is best at lockdown?
65–70% RH from Day 18 through hatch. Avoid opening the incubator; sudden drops risk shrink-wrapping.
What hatch rate should I expect?
Conditions vary, but 50–85% is common. With consistent monitoring and good hygiene, many home hatches reach 70–85%. After hatch, follow chick care in the first 24 hours to reduce post-hatch losses.
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